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Mercedes-Benz Service
Vehicle Climate Control Troubleshooting-Function-Design-Operation Current Passenger Car Models
Service Technology Guide
Daimler AG · Technical Information and Workshop Equipment (GSP/OI) · D-70546 Stuttgart
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Information and copyright
Ordering Workshop Information A wide range of printed workshop information from GSP/OI, such as Introduction into Service Manuals, System Descriptions, Function Descriptions, Technology Guides, Technical Data Manuals and adhesive labels (exception: this Technology Guide is only available via SDmedia) can be ordered as follows: In Germany Through our GSP/OI Shop on the internet Link: http://gsp-ti-shop.de or alternatively E-mail: customer.support@daimler.com Phone: +49-(0)18 05/0 10-79 79 Fax: +49-(0)18 05/0 10-79 78 Outside Germany Please get in touch with the contact person responsible for your market. Product Portfolio Comprehensive information about our full Product Portfolio can also be found at our Internet Portal. Link: http://aftersales.mercedes-benz.com Questions and suggestions If you have any questions or suggestions concerning this product, please write to us. E-mail: christian.barwig@daimler.com or alternatively Address: Daimler AG GSP/OIS HPC R822, W002 D-70546 Stuttgart
© 2011 by Daimler AG This document, including all its parts, is protected by copyright. Any further processing or use requires the previous written consent of Daimler AG, Department GSP/OIS, HPC R822, W002, D-70546 Stuttgart. This applies in particular to reproduction, distribution, alteration, translation, microfilming and storage and/or processing in electronic systems, including databases and online services.
01/2011
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Contents
Preface
Customer reception General Reception protocol for vehicle climate control Stationary heater reception protocol The most common complaints A/C check Stationary heater check
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Workshop Climate control information in detail Stationary heater information in detail Climate control diagnostic tree Stationary heater diagnostic tree
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Knowledge base
Model 164 (M-Class)
Model 164.8 (GL-Class)
Model 169/245 (A-Class/B-Class)
Model 171 (SLK-Class)
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Contents
Model 203/209 (C-Class/CLK-Class)
Model 204 (C-Class/GLK-Class)
Model 207.3/4 (E-Class Coupe/Cabriolet)
Model 211/219 (E-Class/CLS-Class)
Model 212 (E-Class)
Model 215/220 (CL-Class/S-Class)
Model 216/221 (CL-Class/S-Class)
Model 221.095/195 (S-Class Hybrid)
Model 230 (SL-Class)
Model 251 (R-Class)
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Preface
Dear Reader, I am delighted to be able to present you with the fourth edition of the Technology Guide for Vehicle Climate Control. To allow you to work in a more targeted manner, this guide has been updated and added to in close cooperation with experienced mechanics from various workshops and trained staff from service (product support and diagnosis) and development. Models 212 (E-Class), 207 (E-Class coupe/cabriolet) and 221.095/195 (S-Class Hybrid) have been added to this edition, while the information on existing model series has also been revised. All of the new features and additional information have been integrated in the existing document, which now provides a full integrated overview of vehicle climate control in Mercedes-Benz vehicles. As in the previous editions, this document provides summaries of known fault profiles and operating issues and explains these using pictures to help both service advisers and mechanics. In combination with all of the other media available to you, such as Introduction into Service Manuals, Xentry Diagnostics (XD)/Xentry DAS, WIS and TIPS, the information in this document is intended to ensure quick, reliable diagnosis by both service advisors and mechanics to help you with your ultimate aim of performing successful and lasting repairs. This guide should be considered as an aid for everyday use, please use it accordingly.
Yours, Bernd Heinisch (GSP/TPI) Daimler AG After-Sales Engineering Interior MB PC
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Preface
Working with the Vehicle Climate Control Guide The contents of the guide are divided into two main chapters and tailored to the respective user group: - Service advisers (Chapter 1) - Workshop (Chapter 2 and knowledge base) In order to establish this clear distinction between user groups, some information is included in both the service adviser part and in the workshop part. For the service adviser, only information important for the customer interview is included, while the mechanic in the workshop is furnished with more detailed information on diagnosis and repairs (see the introductions to the chapters for service advisers and workshops). Ideally, both the service adviser and the workshop should use the guide. In this way all the important information from the customer can be considered during diagnosis and repair. In return, the customer can be given a competent statement concerning the cause of the complaint and the work carried out. Finally, it only remains to say that the vast majority of complaints can be processed with this guide. Due to the high level of complexity of the climate control system, however, it cannot cover every possible case.
All information was correct as of the copy deadline in December 2010 and may therefore vary from more up-to-date sources.
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The information below is intended to assist you, the service adviser, in customer interviews concerning complaints about vehicle air conditioning systems. Due to the highly complex networking of mechanical and electrical components, the action of external influences and the effect of subjective customer sensations, there may be a wide variety of possible causes for any customer complaint. In order to allow repair work to be carried out quickly and effectively, the customer must provide a description of the complaint that is specific and as detailed as possible, and which can be incorporated into the reception protocol. In your function as a service adviser, your information about the customer's complaint forms the cornerstone of successful diagnosis and repair by the mechanic in the workshop when you forward the reception protocol together with the workshop order. The A/C check and stationary heater check help you to systematically determine the functionality of both systems without using further aids. For this reason it is advisable to conduct these checks together with the customer in the vehicle so that incorrect operation can be ruled out as the cause of the complaint (see notes in chapter "The most common complaints").
The chapter "The most common complaints" contains relevant information to assist you in interviewing the customer. By consistently applying the aids and methods provided here, not only will you be assisting your mechanic in diagnosis and repair work, you will also be helping to rectify the customer's complaint and avoid consequential damage. Furthermore, this procedure creates a single standard of quality for all Mercedes-Benz service partners to follow when receiving complaints and generates a uniform impression with the customer.
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1.1/1
Customer reception
General
Customer reception
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Checklist for customer interviews concerning climate control complaints. Staple to the workshop order. Information only required if not already noted on workshop order VIN or license number or customer name or order number: Follow-up repair: Complaint: Function Noises Odor Detailed description of complaint: Passenger compartment cooling/heating Controls (buttons/display) Blower too weak/too strong/nonfunctional Button flashes constantly Temperature/air distribution Fogged windows No Yes
Duration of complaint: Operating state and ambient conditions during the complaint:
for ______________ min Complaint reproducible Engine: Blower: On Off Yes
Constantly No Warm Cold
Sporadically
On Off Weather conditions: _________________________________ Outside temperature: ______________°C Settings on operating unit/flap positions during complaint
(check off/note settings)
Selected temperature: Left: Right:
______°C
______°C
Other _______________________________________________________
Diagram to clarify settings; valid for all model series Service adviser's findings (results of A/C Check)?
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Customer reception
Reception protocol for vehicle climate control
Customer reception
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Checklist for customer interviews concerning stationary heater complaints. Staple to the workshop order. Information only required if not already noted on workshop order VIN or license number or customer name or order number: Follow-up repair: Complaint: Function Passenger compartment ventilation/heating Controls (remote control/ buttons/display) Test Blower too weak/too strong/nonfunctional Detailed description of complaint: Temperature/air distribution Smoke formation No Yes
Noises
Duration of complaint:
for ________min
Constantly
Sporadically
Operating condition/ ambient conditions If there are problems:
Complaint reproducible Vehicle engine: Fuel gauge: Park position: On Reserve horizontal
Yes Off
No Warm ¼ inclined ½ Cold ¾ 1
Temperatures on A/C operating unit: left: ______ °C/right:_______ °C Weather conditions: _________________________________ Outside temperature: ______________°C
Other _____________________________________________
Service adviser's findings (results of stationary heater check)?
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Customer reception
Reception protocol for stationary heater
Customer reception
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The following pages contain background knowledge intended to assist you, the service adviser, in providing information of value to the customer in the case of the most common complaints. These notes can be taken to the vehicle if necessary while interviewing the customer. The highlighted keywords enable you to quickly find the information relevant to the complaint in hand. For complaints that necessitate a stay in the workshop, detailed information and references to further documents can be found in the chapter "Workshop" or among the model-specific information in the knowledge base.
Odor from air conditioning The complaint "Damp air or odor of laundry just after engine start" is due to physical laws. Fluid that accumulates at the evaporator during operation is absorbed by the air in the evaporator housing when the blower is shut off. When the blower is activated again, this damp air is carried into the interior compartment within the first few minutes. Repairing or replacing components does not remedy the problem. This should be explained to the customer. In the event of odor-related complaints, make sure that there are no objects or dirt in the vehicle that might be causing the odors (luggage compartment, under the seats and floor mats, ashtray, stowage compartments). Furthermore, when air recirculation is active, odors from dirt on shoes or floor mats may be drawn in and circulated in the interior compartment by the blower. Refer to the "A/C Check" to identify the source of the odor. In this context also refer to the note "Automatic air recirculation". Sporadic odors may be caused by temporary environmental influences such as exhaust gases from other vehicles, tunnels, agriculture etc. Fogged windows Possible causes for windows fogged on the inside may be: • Damp in the interior (check floor mats and carpeting) • Dirty windows promote window fogging so it is important to keep the windows clean (inside and outside). • Driving with air conditioning deactivated (explain to the customer that this does not save fuel because the air conditioning systems in current model series feature volume-controlled refrigerant compressors) • Badly set air outlets/flaps (particularly the center air outlets, side air outlets, and defroster outlets). The air flow should be directed onto the fogged areas (see FlashFog logic). • Fouled filters • Driving with air recirculation activated (exacerbated by having the air conditioning off) • Refrigerant compressor shutoff (engine emergency off, anti-icing protection, consumer shutoff) • Due to the "Evaporator drying" function (further information can be found in the "Evaporator drying" function description), the inner windows may become fogged within a period of 1-3 hours of the engine being shut off. In this case, the outside temperature threshold value can be coded to a higher temperature (e.g. 14 °C) on vehicles of model series 204 (as of YoM10) and 207/212 (as of YoM11). Vehicles from before the corresponding modification year can also be equipped with the new SW release. Possible causes for windows fogged on the outside may be: • Positions of center air outlets (diffuse field) or other flap positions. The air flow should be directed away from the fogged areas.
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Customer reception
The most common climate control complaints
Customer reception
The most common climate control complaints
Windows fogged on inside/refrigerant compressor nonfunctional (model series 164/251) The refrigerant compressor switches off at temperatures below 3 °C to protect itself. If, after the refrigerant compressor has switched off, the ambient temperature increases or the driver drives into an area with an outside temperature > 0 °C, the refrigerant compressor only switches on if the temperature of the engine coolant is < 40 °C or the vehicle speed is > 45 km/h. Inform the customer that the system cannot be operated in air recirculation mode in such cases and that the DEFROST button should be activated. Saving fuel by driving with the air conditioning deactivated All current vehicle model series are fitted with volumecontrolled refrigerant compressors (with and without magnetic clutch). These refrigerant compressors are tuned for optimum fuel economy because they are only ever actuated according to requirements. This is not visible from the outside. Therefore, switching off the air conditioning when outside temperatures are low has only a very slight influence on fuel economy, but can encourage fogged windows or odors from the evaporator. Advise the customer to leave the air conditioning switched on all the time. Differences between "identical" vehicles Due to the variety of different versions and new features introduced in the course of each year, differences in the control logic are highly probable. Furthermore, the codings may vary, meaning that fundamentally different control logic systems are involved. For this reason we strongly discourage the use of reference vehicles. This should also be pointed out to the customer if necessary. Differences in new vehicles of existing owners Existing customers with new vehicles should be advised that the functions of the air conditioning can change with every modification year. It is therefore highly likely that functions with which the customer was familiar from his old car have changed in his new vehicle. This should be explained to the customer when selling the vehicle or when complaints are received! Faults do not usually exist with this kind of complaint. Differences of "DEFROST" function Depending on the vehicle model, the powerplant and the modification year in question, there may be differences in the control/actuation of the blower when "DEFROST" is activated. What is more, differences in control are possible in the same vehicle because, depending on the engine heat output, the ambient conditions and other influencing factors, the best possible control curve can be selected in order to deice the windows as quickly as possible.
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Control differences Reactions to changes in the target temperature on the operating unit may vary considerably from vehicle to vehicle depending on the engine heat output, the ambient conditions and other influencing factors. In each case the control unit selects an optimized control curve to achieve the best possible adaptation. For example, it is possible to change only the outlet temperature of the air without changing the blower stage. Similarly, open windows, doors and sliding roof or Vario roof can cause differences in the control of the air conditioning in certain vehicles. Reaction time of air conditioning Air conditioning systems require a certain amount of time to regulate the set temperature. Give the air conditioning time to stabilize properly. A drastic manual increase or reduction in the temperature or blower stage (e.g. when starting up and in extreme outside temperatures) does not normally produce quicker reactions. Implausible regulation – single/multiple-zone sun sensor Multiple-zone sun sensors have a substantial influence on temperature control. When the sunlight hits the vehicle at an angle, this may result in extreme differences in the outlet air temperatures and blower outputs between the left and right sides. This effect can also occur under cloudy skies due to UV radiation. The sensitivity of the sun sensor can be coded with Xentry Diagnostics (XD)/Xentry DAS.
Implausible regulation – outside temperature indicator temperature sensor If you cannot understand why the climate control is operating in a certain way, the outside temperature indicator temperature sensor (B14) should also be taken into account. Through a simple plausibility check (e.g. comparison of outside temperature value shown on instrument cluster) while driving when the complaint occurs, it is possible to rule out the possibility that the control unit of the air conditioning is receiving an incorrect outside temperature value and thus regulating incorrectly. Weather-related effects (e.g. due to snow and ice) or mechanical impairment (e.g. a sensor unclipped by a foreign object) must also be considered. You should also take the information in the model series-specific "Climate control functions" section under the "Outside temperature" point into account. Implausible regulation on model series with several interior temperature sensors In the event of implausible regulation or nonfunctional components: check interior temperature sensors present. Temperature differences Temperature differences between the driver and front passenger side are normal in certain model series and should be compensated for by regulating the operating unit manually.
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Customer reception
The most common climate control complaints
Customer reception
The most common climate control complaints
Temperature differences between left and right Warning for air-regulated systems: In the event of temperature differences between left/right do not replace the shutoff valve. Separate valves (pulsed valves) for the left and right sides exist only in waterregulated systems. Poor control quality/temperature differences/ intermittently too hot or too cold/cold feeling The customer complaint "poor control quality/ temperature differences/intermittently too hot or too cold/cold feeling" may be caused by leakage in the bodywork. This applies above all when the complaint occurs in conjunction with abrupt vehicle speed changes (e.g. braking after driving fast). In order to provide the engine with the required power at very high speeds or acceleration, the output of the refrigerant compressor can be reduced. This can cause the complaint "Blower output too warm". This is normal and does not justify replacing parts. Temperature differences/blower output occasionally too warm (hybrid vehicles) The customer complaint "Temperature differences/ blower output occasionally too warm" can be due to temporary limitation of the output of the electric refrigerant compressor. Please note that output limitation of the electric refrigerant compressor does not cause a fault memory entry because it is a normal and necessary protection function of the battery management system. Replacing parts does not remedy the problem. Refer to the note "Consumer shutoff". Cold feeling after driving for a long time The customer complaint "cold feeling after driving for a long time" is usually due to subjective sensations or settings on the air conditioning. The cause of the customer complaint "cold feeling after driving for a long time" is a natural reaction of the body, which adopts a state of rest after long periods without physical exertion and produces less heat. Since freedom of movement is severely restricted inside the vehicle, the blood flow in the legs especially is impaired. The result is inadequate blood circulation, which can lead to a "cold feeling" in the legs. If the customer complains of a "cold feeling after driving for a long time", advise them to adjust the temperature of the air conditioning manually to suit their needs and on long journeys to take regular breaks with physical exercises (rule of thumb:every 200 kilometers or every two hours). Also check the settings for the rear blower (cold air in the rear compartment can travel into the front footwells.)
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"Cold feet" (with code 582 Rear air conditioning) If the customer complains of "cold feet", first check the settings in the rear compartment. If the rear is set to "cooling", it can happen that the cold air travels forwards from the rear under the seats. No or poor heat output Depending on the engine model installed, this may be caused by the heating system shutoff valve (Y16/2) at the engine. This valve is controlled via the engine control unit. Please check accordingly. Poor heat output/cooling output in rear The control response in the rear can be delayed because the air or hot water (with code 582 Rear air conditioning) has to travel a longer distance from the front air conditioner housing or engine to the rear air vents and can thus cool down or heat up on the way. Poor heat output/cooling output in rear (model series 164/251) The climate control system reacts with a delay in the rear compartment because the first seat row is given priority. Cold feeling at the rear/no heating at the rear (without code 582) The rear center air outlet always takes its air from the coolest point. For this reason cool air emerges from the rear center air outlet even when heating mode is active at the front. In the case of this complaint it is advisable to close the rear center air outlet. Warmer air is then supplied via the rear footwell air outlets and also via the B-pillar on model 221. Replacing parts does not remedy the problem.
Knocking noises from pulsed valves Knocking noises in model series with water-regulated air conditioning systems (see chapter "Knowledge base") are normal. The noises are caused by the pulsed valves. In residual heat mode these noises are more obvious because they are normally overlaid by other noise sources while driving. Replacing parts does not remedy the problem. Gurgling noises (model series 171) Air in the cooling-water circuit can cause gurgling noises. The problem can be remedied by evacuating the system by vacuum and then refilling the coolingwater circuit at 1.4 bar. Then allow the engine to warm up at a pressure of 1.4 bar. Sound level of electric refrigerant compressor (hybrid vehicles) Due to the low engine sound level and automatic engine stops, isolated customer complaints are received about the sound level of the electric refrigerant compressor. Up to a refrigerant compressor speed of approx. 3000 rpm, the sound level is perceived as a "non-distracting buzzing sound" but above this speed the sound level is somewhat higher and audible from the outside. If the electric refrigerant compressor is producing a different sound level, the refrigerant compressor may not be supplying its full output during control operations. By checking the condition (coloration, residues from mechanical wear) of the refrigerant and refrigeration oil, it is possible to rule out the possibility that the electric refrigerant compressor is mechanically damaged and thus causing excessive noise. Replacing parts without prior inspection will not rectify the problem.
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Customer reception
The most common climate control complaints
Customer reception
The most common climate control complaints
Flow noises/whistling noises in the interior at high vehicle speeds (model series 216/221) At higher speeds and with the flaps in certain positions, there may be turbulence in the air stream which may cause flow noises. Possible remedy: code speeddependent recirculated air via Xentry Diagnostics (XD)/Xentry DAS. More air from one outlet than from others If the customer complains of "more air from one outlet than from others", note that when some air outlets are closed, the air flow is distributed among the remaining outlets in the vehicle and this can result in air flows of varying intensity. The climate control can also create such differences intentionally (e.g. to compensate for the angle of the sun). No air or insufficient air emerging although the blower is running If the blower is running but there is no air at any outlet, this can be an indication of icing in the evaporator. This symptom disappears when the vehicle and the engine are left off for a certain time (the ice at the evaporator thaws). To rule out the possibility of a defective evaporator temperature sensor (B10/6), also check the evaporator temperature sensor (B10/6) for plausibility using Xentry Diagnostics (XD)/Xentry DAS for this customer complaint. No blower setting bars on the display in "DEFROST" or "REST" mode Depending on the model year, when the "DEFROST" or "REST" function is activated the blower setting bars on the display disappear and a fixed blower setting and temperature are set. As long as this function is active, the customer will not be able to intervene in the control process. ACOFF or A/C button lit/flashing constantly or ACOFF A/C button nonfunctional The complaint "no cooling output or ACOFF or A/C button lit/flashing constantly" indicates that the air conditioning system is empty or not sufficiently full. The refrigerant compressor has been shut off for its own protection. The detailed procedure can be found in WIS under "Empty/evacuate/refill air conditioning and check for proper operation and leaks". "AC-OFF" in central climate control menu on the COMAND display cannot be deactivated (model series 216/221) The complaint "AC-OFF in central climate control menu on the COMAND display (A40/8) or on the SPLITVIEW display (A40/10) (with code 867) cannot be deactivated" indicates that the air conditioning system is empty or not sufficiently full. The refrigerant compressor has been shut off for its own protection. The detailed procedure can be found in WIS under "Empty/evacuate/refill air conditioning and check for proper operation and leaks" (AR83.30-P-1760SX).
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Air conditioning does not cool (old model series up to model series 211/219) An important change in the operation of air conditioning systems (control logic) is the assignment of the "A/C" or "ACOFF" button. Please be sure to point this out to the customer. The air conditioning is cooling or the refrigerant compressor is operating - when the "A/C button" is lit or - the "ACOFF button" is off. When replacing operating units in particular, please note that there may be differences in the control logic and expressly advise the customer of this. Before replacing an operating unit, always perform a circuit 30 reset in order to check the function. Air conditioning switches on automatically (hybrid vehicles) When the high-voltage battery module requires cooling, the battery management control unit issues a cooling request. This can result in the electric refrigerant compressor starting up audibly e.g. with the start/stop function active. The air conditioning operates with the same settings prior to it being switched off. Air conditioning cannot be switched off (hybrid vehicles) If the high-voltage battery module still requires cooling, the air conditioning cannot be shut off (disable function: the deactivation is reversed after 2 s). The air conditioning remains switched on after the battery is cooled.
Noises after switching off If the customer complains about "whistling or hissing noises after switching off", point out that these can be produced by the equalization of gas pressure at the expansion valve. These noises can even occur a long time after the vehicle is switched off. Other noises after switching off can be caused by actuator motors moving into their park position (as much as several minutes after switching off the ignition). Replacing parts does not remedy the problem.
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Customer reception
The most common climate control complaints
Customer reception
The most common climate control complaints (functions)
The following pages contain important information and background knowledge about climate control functions.
Automatic air recirculation Automatic air recirculation is not indicated by the function LED. Depending on the equipment installed, automatic air recirculation is activated e.g. in the case of high outside temperatures or poor quality of the fresh air (pollutants). Automatic air recirculation is not possible when the following settings are active: • Air conditioning deactivated (note control logic of A/C – ACOFF buttons) • Maximum heating • DEFROST • In vehicles with activated charcoal filter button on the operating unit. If there are pollutants in the air, automatic air recirculation is only possible when the activated charcoal function is activated using the activated charcoal filter button on the operating unit (see chapter "Knowledge base") • In cold temperatures (only at temperatures above approx. 5 °C, even if the activated charcoal filter is activated) The sensitivity of the pollutant sensor changes according to the ambient conditions. For this reason, exhaust odors after driving for a long time under identical environmental conditions may be normal. Air recirculation flap closes when air conditioning is switched off When the air conditioning is switched off using the "0 button" or the blower is set to "0" (depending on equipment installed), the air recirculation flap is closed. The function can be set via Xentry Diagnostics (XD)/Xentry DAS. Reduction of door closing forces through flap adjustment When the ignition is off and one of the doors is opened, the fresh air/recirculated air flap and the ram air flap (with code 581) are partially opened by the fresh air/recirculated air/ram air flap actuator motor. This reduces the door closing forces. The function can be set via Xentry Diagnostics (XD)/Xentry DAS. Convenience closing Convenience closing (tunnel mode switching) is only possible provided that all the windows and the tilting/ sliding roof (if installed) are normalized. If necessary, normalize the components with Xentry Diagnostics (XD)/Xentry DAS. If the air recirculation mode button is pressed briefly after convenience closing has occurred, the previously stored positions (windows, sliding roof) are lost. In vehicles fitted with activated charcoal filter button, this can also be used to operate the convenience closing feature. For a detailed description of the "convenience closing" function, refer to the explanation of the "air recirculation mode button" in the relevant model description.
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Speed-dependent ram air mode To prevent the air feed into the interior compartment from increasing as the vehicle speed increases, the fresh air/recirculated air flap (with code 580) and the ram air flap (with code 581) are adjusted on a speeddependent basis. The higher the speed, the further the ram air flap is closed. FlashFog logic To prevent windows from fogging up, no air is directed at the windshield for a short time after engine start. This function cannot be prevented even by adjusting the flaps manually. Only the defrost function disables the FlashFog feature. The duration of this function can vary depending on the model series and the ambient conditions. In the event of complaints, this should be explained to the customer. Defrost function When the Defrost function is activated, the refrigerant compressor is actuated to dry the air as effectively as possible. Anti-icing protection To prevent the refrigerant compressor from icing up, the values from the evaporator sensor are checked constantly while the air conditioning is operating. If the values approach the 0 °C limit, the control unit turns down the refrigerant compressor in order to prevent icing. This produces temperature fluctuations/surges at the evaporator sensor which may be perceived by sensitive customers. Please note that the anti-icing protection of the refrigerant compressor does not cause a fault memory entry because it is a normal and necessary protection function of the air conditioning system. Replacing parts does not remedy the problem.
Evaporator drying (as of model series 204) In order to counteract odors from the evaporator in the interior compartment and prevent fogging of the windows when the air conditioning starts up, the evaporator of the air conditioning system is dried. One hour after the engine is shut off, the instrument cluster transmits the request to dry the evaporator to the AAC [KLA] control and operating unit via interior CAN, which initiates drying of the evaporator. To do so, the blower is activated at its lowest stage for 30 min. This coding is coded to "active" or "not active" at the plant depending on the model series and country of sale. Cold start lockout The cold start lockout function prevents a high blower speed from being set in cold outside temperatures. This function is purely for the customer's comfort. As the temperatures in the heating circuit rise, the blower speed setting is increased. Center air outlet In cold outside temperatures or in heating mode the center air outlet can be closed automatically by the air conditioning control unit in order to improve comfort levels. Because warm air rises, this results in more uniform heating of the interior compartment. Air ducting (model series 221/216) On model series 221/216, the air distribution can be changed either using the buttons in the upper control panel or electronically via the central display.
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Customer reception
The most common climate control complaints (functions)
Customer reception
The most common climate control complaints (functions)
Cold air reduction (model series 211/219) If installed, the cold air reduction feature (see model description for an explanation) can be used in heating mode to direct cooler air to the center air outlet than is set on the operating unit. In model series 211 the cold air reduction function is deactivated in AUTO mode. Warm air increase (model series 230) The warm air increase feature (if installed; see chapter "Knowledge base" for an explanation) opens the center air outlet in heating mode. The temperature of the emerging air is regulated according to the target temperature selected on the operating unit. Blower lowering via voice control system (VCS) (as of model series 204) With the voice control system active, the blower output is limited to 50%. To do so, the radio and navigation unit or the COMAND controller unit transmits the status of the voice control system to the automatic air conditioning control and operating unit via interior CAN. This then limits the blower output. Reduction of blower output with ECO start/stop system When the blower for automatic air conditioning is active, the blower output is reduced. At warm ambient temperatures, the system switches to air recirculation mode depending on the specified temperature setting. Consumer shutoff Most Mercedes-Benz vehicles feature a consumer shutoff function. If the on-board power supply voltage is too low, e.g. when several consumers are switched on just after moving off or when the engine is idling, certain convenience functions may be stepped down or shut off entirely. These functions include the vehicle climate control, the "residual heat" blower control (can also be shut off while stationary) and the stationary heater or heater booster (PTC). Although an increase in the blower stage can be seen on the display in the case of a temporary consumer shutoff, the blower itself does not react. Likewise it is possible that the rear window heater may not start up even though it has been activated and activation is confirmed by the lighting of the function LED on the operating unit. A fault is not stored in the case of a temporary consumer shutoff. When these complaints are encountered, it is therefore absolutely essential to find out the precise ambient and driving conditions that existed at the time the complaint occurred. Actuation of rear window heater In all model series apart from model series 164/251, the rear window heater is regulated by the rear SAM and not by the AC operating unit. However, in all models the rear SAM receives and passes on the "rear window heater" signal (including model series 164/ 251). For this reason, it is absolutely essential to check the rear SAM component as well in the case of a malfunction of the rear window.
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Switch-on time of rear window heater After the rear window heater button is actuated, the rear window heater is generally switched on immediately and its operation is confirmed by light-emitting diode (LED) in the button. However, if there is a temporary on-board electrical system undervoltage (less than 5 min), the LED may light up even though the rear window heater is shut off. Refer to the note "Consumer shutoff". The duty cycle (automatic shutoff) of the rear window heater depends on the outside temperature and vehicle speed. These control features are intentional. Please explain this logic to the customer. Replacing parts does not remedy the problem. Key-dependent storage of air conditioning settings (model series 211/219) Dependent on the equipment variant of the air conditioning system and the vehicle model, key-dependent air conditioning settings can be saved (memory function). In other words, different settings for the air conditioning can be saved according to which transmitter key is used. Air conditioning starts up with a delay Under certain circumstances, temperature changes when the vehicle is parked (e.g. day/night differences) may cause the refrigerant compressor to start up with a delay when the engine is started. This is due to natural causes. Repairing or replacing components does not remedy the problem.
Refrigerant compressor startup condition (model series 164/251) In model series 164/251 the outside temperature value is one startup condition for the refrigerant compressor. With rising outside temperatures and vehicle speeds below 30 km/h, the colder value is retained. This can be one reason for the air conditioner failing to start up at cold outside temperatures after the vehicle is moved into a warmer environment (e.g. workshop, underground garage). No "click" when switching on the air conditioning All current Mercedes-Benz model series are fitted with volume-controlled refrigerant compressors with and without magnetic clutch depending on the variant. The typical "click" when a refrigerant compressor without magnetic clutch starts up no longer occurs. It is no longer possible to hear the refrigerant compressor switching on. On refrigerant compressors with magnetic clutch, their activation can be heard by a quiet "click". Note that the switch-on and switch-off points may be delayed. In case of doubt, make sure that the shaft on the refrigerant compressor is turning when the engine is switched on. ACOFF in central display (model series 221/216) On model series 221/216 there is, for the first time, no switch in the upper control panel for activating/ deactivating the refrigerant compressor. The system is activated/deactivated electronically via the central display.
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Customer reception
The most common climate control complaints (functions)
Customer reception
The most common climate control complaints (functions)
Outside temperature value Outside temperature indicator temperature sensor (B14): The outside temperature value is stored as soon as the vehicle travels slower than 30 km/h. This value is adjusted in stages only when the vehicle travels faster than 30 km/h for a certain length of time. When the vehicle is stationary, therefore, a plausibility check of this sensor value using Xentry Diagnostics (XD)/Xentry DAS is not meaningful because only the stored value for the outside temperature can be retrieved. There is no possibility to reset the stored outside temperature value. Should you encounter complaints concerning the temperature control which cannot be reproduced while stationary, we recommend that you attempt to reproduce the complaint under the conditions described by the customer (see reception protocol). PTC operation with refrigerant compressor switched off The PTC heater booster is coded at the plant to operate irrespective of the position of the A/C button (refrigerant compressor on/off). This ensures that the heater booster function is available even with the refrigerant compressor switched off e.g. in winter. The coding can (except on model series 203) be changed via Xentry Diagnostics (XD)/Xentry DAS. If an electric heater booster is installed on model series 203, it can be programmed in the instrument cluster on certain variants for operation with the refrigerant compressor switched off. Programming the heater booster via Xentry Diagnostics (XD)/Xentry DAS is not possible on model series 203. Switch on/off conditions of PTC heater booster (model series 211/219) ACOFF button on vehicles up to 11/04: With the ACOFF button activated, the PTC heater booster is switched off. Vehicles as of 11/04: PTC heater booster is no longer switched off/affected by the ACOFF button. Consumer shutoff: If consumer shutoff stage 1 or 2 is active, actuation of the PTC heater booster is disabled. Remedy: higher engine speeds. On-board electrical system: If several consumers of the on-board electrical system are switched on simultaneously (e.g. driving lights, audio system, rear window heater and seat heaters), the output of the alternator is not sufficient to ensure proper operation of the PTC heater booster. Remedy: higher engine speeds. Booster blower (model series 203) In model series 203 with code 581 an additional blower motor (booster blower) may be installed in the rear compartment of the vehicle. When the blower is installed, there is an additional potentiometer on the rear center air outlet selector wheel. Visually there is no discernible difference in the installed condition. For details on identification refer to the component description for the rear blower motor. Rear blower actuation (model series 204, 207, 212) To prevent excessive noise from high blower speeds, actuation of the rear blower while driving is limited to max. 3500 rpm (70%). A speed of 5000 rpm can be reached via actuation with Xentry Diagnostics/Xentry DAS.
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Rear air conditioning systems (with code 582) Rear air conditioning systems only draw in interior air (please note this in the event of odor-related complaints). Rear operating unit resets settings (model series 164/251) In model series 164/251 the custom rear compartment settings are erased and reset to 22 °C and automatic mode after approx. 30 minutes with the ignition switched off. This is intentional. Replacing components does not remedy the problem. Rear operating unit display A blower stage bar is displayed on the rear operating unit despite the blower being inactive. Model series 171 without air conditioning In some countries, model series 171 with M271 is not fitted with an air conditioning system in the basic variant as standard equipment. Omission of second heat exchanger with code 582 (model series 251) Shortly after production start-up, the second heat exchanger in the rear was omitted from model series 251 with code 582 and along with it the additional heat output for the third seat row. AUTO mode on model series 169/245 with code 580 Some of the flaps are adjusted via Bowden cables, in which case no automatic flap control is possible.
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Customer reception
The most common climate control complaints (functions)
Customer reception
The most common stationary heater complaints
The following pages contain important information and background knowledge about stationary heaters.
Stationary heater ex plant since 1.1.2011 (model series 204) On model series 204, the stationary heater special equipment has been offered since 1.1.2011. Previously, the stationary heater special equipment was not available ex plant. Stationary heater nonfunctional — Consumer shutoff The event "Consumer shutoff" in the battery control unit prevents the stationary heater from being activated in the event of undervoltage in the on-board electrical system or causes it to shut off. If consumer shutoff is active or stored in the control unit, the onboard electrical system and/or the on-board power supply voltage/vehicle battery(-ies) must be checked. Stationary heater nonfunctional – Consumer shutoff due to short-distance operation The battery cannot reach its optimum charge level if the vehicle is driven over short distances at a low engine speed with high current consumers frequently switched on (e.g. heated rear window, heated seats etc.). Rule of thumb: Heating time = Driving time. Stationary heater nonfunctional – defective LED A defective LED in the stationary heater switch on the control panel prevents the stationary heater from operating, the stationary heater switch is defective. The fault 'LED defective' is stored in the stationary heater control unit. Stationary heater nonfunctional – empty tank To ensure that the stationary heater operates properly, the vehicle tank must be at least ¼ full and the vehicle should be parked almost horizontally to ensure optimal fuel intake. Stationary heater nonfunctional – fault interlock After 3-6 failed start attempts (model series-dependent), the heater unit is disabled. The stationary heater can only be reactivated after it is enabled using Xentry Diagnostics (XD)/Xentry DAS. Stationary heater nonfunctional – crash safety shutoff In the event of a crash, the stationary heater or heater booster function is permanently switched off. The interlock can only be released via Xentry Diagnostics (XD)/Xentry DAS. Stationary heater nonfunctional – heater overheated Overheating protection may be activated by air in the water circuit. As a result, the water circuit must be inspected for leaks and then bled. The interlock can only be released via Xentry Diagnostics (XD)/Xentry DAS.
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Stationary heater nonfunctional on diesel vehicles Ensure that the fuel is suitable for winter conditions, especially in the transitional period between seasons. The fuel line can be jellified by summer diesel. Stationary heater nonfunctional, switches off or smokes after long idle period An extended period of non-use, e.g. over the summer months, can result in air bubbles in the fuel line. Several start attempts should be carried out until the stationary heater starts up. To "burn off" the heater unit, the stationary heater must then be left on for at least one entire heating cycle. Stationary heater shuts off when engine is switched off (model series 164/251) In the context of battery management, the stationary heater is also switched off on model series 164 and 251 after the engine is switched off. This function was first introduced in series production in September 2009. Maximum heating and ventilation duration Depending on the default setting and ambient conditions, the maximum heating and ventilation duration of the stationary heater is 50 min. This is a default setting which can be changed via Xentry Diagnostics (XD)/Xentry DAS. As of model series 204, 207, 212, 221/216, the optimal heating duration is automatically calculated by entering the desired departure time. This also depends on: the temperature settings on the AC operating unit, the interior and outside temperature as well as the temperature of the coolant.
Logic change regarding start/departure time For the first time on model series 221, the departure time and not the start time for the stationary heater is entered in the instrument cluster/remote control. Stationary heater button – preselection time menu (model series 211/219) When the button is actuated for less than 2 s only the preselection time menu is called up – with the system switched off. The system will be activated if the button is pressed for a longer time. When the system is switched on, pressing the button immediately switches it off – without the preselection time being called up. Remote control T70/T90/T100 Remote control T90 replaces remote control T70. T90 gives the user feedback about whether the switch on/ off signal has been received. The T90 was deployed as of May/June 2004 in all model series except 203/ 209. It was deployed in model series 203/209 in November 2004 and in the Maybach in September 2004. The T100 replaces the T90. The T100 was first deployed in model series 221 as of June 2006. Stationary heater remote control nonfunctional Empty batteries or battery contact problems can impair the function of the stationary heater remote control.
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Customer reception
The most common stationary heater complaints
Customer reception
The most common stationary heater complaints
Range of remote control The range and/or operation of the remote control can be influenced or impaired by a number of different factors (e.g. garage door openers, cordless telephones, transmitter masts, power lines) or obstacles (e.g. buildings). Manual teach-in of stationary heater remote control (T100) Hold down the instant heat button in the control panel until the red LED in the instant heat button starts to flash; release button; immediately press the OFF button on the remote control; the teach-in process is complete. Max. 3 remote controls can be stored. Alternatively, the teach-in process can be carried out with Xentry Diagnostics (XD)/Xentry DAS. Stationary heater remote control nonfunctional after disconnecting/connecting vehicle battery The taught-in transmitter can be lost when the vehicle battery is disconnected and then reconnected if conditions are unfavorable. Teach in the remote control again. Radio failure message "¢FAIL" (all model series with remote control T100) The message "¢FAIL" on the display of the remote control can also be caused by inadequate range or reduced range in the event of heavy interference (e.g. underground garage). Always check before replacing! Green LED of remote control does not light up when switching off stationary heater with remote control (model series 211) Error in operating instructions, it should read "red LED lights up when switching off". Clicking noises during stationary heater operation The fuel metering pump of the stationary heater can produce pulsation noises which are normal. Check the metering pump for correct seating and check the soundproofing (pump may not contact body). Heating temperature preselection/insufficient heat output when activated with preselection via instrument cluster/remote control The stationary heater heats or ventilates the interior for the set departure time depending on the outside temperature, inside temperature and the specified temperature value set on the automatic air conditioning control and operating unit (N22/7). Thermo Top V (model series 164/251) As of September 2006, Thermo Top V stationary heaters from Webasto have been installed in model series 164/251.
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Retrofitted stationary heater This guide only deals with stationary heaters that are installed in the vehicle at the plant (identifiable via SA code 228). The advice contained in this guide may help to troubleshoot retrofitted systems but has only been tested on systems installed ex plant. For questions regarding complaints about retrofitted variants, contact your relevant LC or the manufacturer Webasto at the hotline number +49 (0)1805-932278. Mon-Fri 8 a.m. – 6 p.m. Stationary heater run-on If the combustion air blower of the stationary heater is in the run-on phase, the stationary heater cannot be activated even though the LED is on. Run-on of fossil fuel heater booster The fossil fuel heater booster continues to run for a period when switched off. This function burns off the fuel remaining in the device and the heater booster is also cooled by the internal blower run-on after the combustion process finishes. Poor heat output after cold start with OM642 (model series 216/221) As of modification year 01/2007, fossil fuel heater boosters are no longer installed on OM642 as standard. To provide sufficient heat output after a cold start, the engine operates in heating/combustion mode during this period.
PTC heater booster (model series 216/221) On model 221 with diesel engine, the PTC heater boosters are installed in the heat exchanger. Stationary heater repair method On many stationary heaters (Thermo Top C), it is possible to replace the burner insert individually, see SI83.70-P-0010A. For wiring harness malfunctions, see SI83.70-P0001B.
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Customer reception
The most common stationary heater complaints
Customer reception
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Explanation of the symbols used in the A/C Check diagnostic trees:
Symbol
Explanation
Ignition at stage 2, blower off
Test steps, notes, causes, measures and further information
Noise present?
Yes
Branch at which you must make a decision with "Yes" or "No"
No
Continued on the next page
2
Continued on the next page
Noise complaints
Topic of customer complaint in the relevant chapter color
Note:
Do not check flaps in Auto mode, but actuate them individually
General information
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Customer reception
A/C Check
Customer reception
A/C Check
Note: All checks can be performed manually without testing unit. Identify customer complaint
No
Is detailed information available about the customer complaint?
Observe the notes in chapter "Customer reception: 1.1 and 1.3". There you will find descriptions of customer complaints, for example. In many cases, replacing parts does not remedy the problem because it is due to a normal function rather than to a defect in the air conditioning system. Yes
No
Can the complaint be demonstrated by the customer?
Yes Have the customer demonstrate the complaint.
No
Complaint occurred?
Note: correctly
Was the air conditioning activated (A/C – AC )?
off
Yes
Can incorrect operation No be ruled out, or is the complaint justified? Refer to "The most common complaints".
Advise the customer how to operate the air conditioning; point out that settings may have to be changed (e.g. cold feeling). Refer to "The most common complaints".
Yes
Fill out handover protocol Hand vehicle over to workshop No repairs
Perform A/C Check according to complaint:
Function complaints
Odor complaints
Noise complaints
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Observe the notes in chapter "Customer reception: 1.1 and 1.3". e.g. "Windows fogged up" or "Does not cool"
A/C Check for function
Start engine
Activate air conditioning Observe control concept (A/C – ACoff).
Set air conditioning to setting for maximum cooling or maximum heating according to the complaint, and set blower for maximum output.
Note:
The FlashFog logic prevents actuation of the outlets for the wind shield for approx. 30 s.
Note:
Do not check the flaps in Auto mode, but actuate them individually.
Note:
If installed, note cold air reduction feature.
Manually check individual flaps: Is sufficient air noticeable at all flaps? Manually set the following flap positions in sequence and check: • Center air outlet (1) (note cold air reduction and center outlet kinematics depending on equipment installed, see model description) • Side air outlets in dashboard (2) • Footwell air outlets (3) • Windshield (4) • Diffuser outlet (5) • Rear compartment - Center vent (6a) - Side vents (6b) - Footwell vents (6c)
No
Sufficient air after 5 min at the latest—Condition: Engine coolant warm (depending on complaint warm or cold) noticeable at all flaps (check flap positions individually in succession)?
Yes
Fill out handover protocol, hand vehicle over to workshop
Yes
Can incorrect operation be ruled out as cause?
No Advise the customer how to operate the air conditioning; point out that settings may have to be changed (e.g. cold feeling). Refer to "The most common complaints".
No repairs
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Customer reception
A/C check for function-related complaints
Customer reception
A/C check for odor-related complaints
A/C Check for odor Note: When air recirculation mode is active, odors from dirt on shoes or floor mats may be drawn in and circulated in the interior compartment by the blower.
Complaint "Odor of damp/ water vapor (laundry)" only for a few minutes after engine start, then gone?
Yes
Not a complaint. Point out to the customer that this is normal operation of air conditioning. No repairs.
Note: No
In the first few minutes after an engine start, damp air may be blown out ("laundry smell"). This is due to natural causes. Repairs do not remedy the problem.
Check vehicle interior (e.g. trunk or under the seats) for foreign objects/ contamination/vapors: • Food leftovers Odor inside the closed vehicle (ignition off)? • Spilt fluids Yes • Air outlets for fluids • Cigarette smell/ashtrays • Animal hair (pets) • Air fresheners • Interior (e.g. instrument panel) No • Damping mats (e.g. smell test with shift gate opened) • Miscellaneous
No
Odor due to foreign objects?
1 Visual inspection of engine compartment for foreign objects/dirt 2 Check interior combination filter for contamination and replace if necessary 3 Noise check of interior blower fan for unobstructed movement/foreign objects (from engine side); remove foreign objects if necessary 4 Visual check of duct between engine compartment and blower, clean if necessary
Yes
Offer the customer interior cleaning if necessary (at the customer's expense)
No
Complaint justified?
No
Odor eliminated?
Yes
Yes Inform customer No repairs Fill out handover protocol, hand vehicle over to workshop
Return vehicle to customer
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A/C Check for noise
Note: in the
Noises can be localized both acoustically and by sensing vibrations. Observe safety information for work engine compartment with the engine running! When working on the blower, set ventilation to stage 0.
Ignition on, blower off Note: Slight noises, e.g. due to suction fan run-on, fans for interior temperature sensors or any additional fans for electronic components (e.g. radio, relays) etc. are normal.
Noise present?
Yes
Complaint justified?
No
Advise the customer No repairs
No
Yes
Ignition on. Switch on front and rear blower in turn
Fill out handover protocol, hand vehicle over to workshop
Noise present?
Yes
Noise from interior in direction of AC housing?
Yes
• Check interior combination filter for contamination and replace if necessary. • Noise check of interior blower fan for unobstructed movement/foreign objects; remove foreign objects if necessary. • Visual check of duct between engine compartment and blower, clean if necessary.
No
No
Start engine
Possible noises: Damaged air flaps/actuator motors
Note:
The FlashFog logic prevents actuation of the outlets for the windshield for approx. 30 s.
Note:
Do not check the flaps in AUTO mode, but actuate them individually.
Continued on the next page
1
Continued on the next page
2
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Customer reception
A/C Check for noise-related complaints
Customer reception
A/C Check for noise-related complaints
Continued
1
Continued
2
Possible noises in engine compartment • Refrigerant compressor noises • Hissing noises • Vibration noises • Noises from area of steering system, power steering pump • Noises from belt drive
Manually check individual flaps: Is sufficient air noticeable at all flaps? Manually set the following flap positions in sequence and check: • Center air outlet (1) (note cold air reduction and center outlet kinematics depending on equipment installed, see model description) • Side air outlets in dashboard (2) • Footwell air outlets (3) • Windshield (4) • Diffuser outlet (5) • Rear compartment - Center vent (6a) - Side vents (6b) - Footwell vents (6c)
Complaint justified?
No
Advise the customer No repairs
Yes
Fill out handover protocol, hand vehicle over to workshop
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Note:
All checks can be performed manually without testing unit.
Identify customer complaint
No
Is detailed information available about the customer complaint?
Observe the notes in chapter "Customer reception: 1.1 and 1.3". There you will find descriptions of customer complaints, for example. In many cases, replacing parts does not remedy the problem because it is due to a normal function rather than to a defect in the air conditioning system. Yes
No
Can the complaint be demonstrated by the customer?
Yes
Have the customer demonstrate the complaint.
• Note on transitional period between seasons: Is the fuel in the tank suitable for winter conditions? The STH fuel line may be jellified. • Was the fuel tank at least ¼ full when the complaint occurred?
No
Complaint occurred? Yes
Continue with
1
Continue with
2
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Customer reception
Stationary heater check
Customer reception
Stationary heater check
Continued Note: On model series 211, 251 and 164, the specified temperature for the stationary heater can be preselected in the range from 20 to 24 °C. At temperatures lower than 20 °C, the temperature is automatically regulated to 20 °C and at temperatures greater than 24 °C, the temperature is automatically regulated to 24 °C. Continued
1
2
Yes
Yes
Note: Is the fuel tank at least ¼ full? No
Yes
Are the batteries of the remote control empty? No
Note: An insufficient heating period or excessively low preselected temperature on the control panel can result in the interior compartment not being preheated to the desired temperature. Inform customer about function: STH heats up to the temperature set on the AC control panel.
Yes
Customer complaint about insufficient heat output?
No
No
Can incorrect operation be ruled out as cause or is complaint justified? Observe the notes in chapter "Customer reception: 1.1 and 1.3".
Yes Advise the customer how to operate the stationary heater, point out that settings may have to be changed (e.g. activation time/departure time, temperature preselection). Observe the notes in chapter "Customer reception: 1.1 and 1.3". Fill out handover protocol, hand vehicle over to workshop
No repairs
Perform STH check as per complaint
Function complaints
Noise complaints Noise complaints
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Note: Observe notes in chapter "Customer reception: 1.1 and 1.3"., e.g. "STH smokes" or "STH nonfunctional".
STH function check
Activate STH
Note: Is the fuel tank at least ¼ full?
Note: Are batteries of remote control empty?
No
Is sufficient warm air noticeable after 7 minutes at the latest at the windshield outlets?
Yes
Fill out handover protocol, hand vehicle over to workshop
Yes
Can incorrect operation be ruled out as cause?
No
Advise the customer how to operate the stationary heater, point out that settings may have to be changed (e.g. start time). Observe the notes in chapter "Customer reception: 1.1 and 1.3".
No repairs
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Customer reception
Stationary heater check for function-related complaints
Customer reception
Stationary heater check for noise-related complaints
STH function check Note: Noises can be localized both acoustically and by sensing vibrations. Observe safety information for work in the engine compartment with the engine running! When working on the blower, set ventilation to stage 0.
Activate STH
A certain level of noise due to combustion and air intake is unavoidable, particularly when the STH is started, and is considered normal. The noise can be optimized by adjusting the air/fuel ratio in the workshop.
Are noises present in engine compartment? No
Yes
Complaint justified? Yes
No
Advise the customer No repairs
Fill out handover protocol, hand vehicle over to workshop
• Check interior combination filter for contamination and replace if necessary Are noises present in interior compartment? No Yes • Noise check of interior blower fan for unobstructed movement/foreign objects; remove foreign objects if necessary • Visual check of duct between engine compartment and blower, clean if necessary
Complaint eliminated No
Yes
Advise the customer No repairs
Yes
Complaint eliminated? No
Fill out handover protocol, hand vehicle over to workshop
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The following pages provide you, the mechanic, with important information and background knowledge concerning common customer complaints about vehicle air conditioning systems. As well as instructions on the use of the diagnostic trees, you will also find information which will enable you to carry out diagnosis and repairs quickly and successfully. The information in this chapter is also available in abbreviated form in the customer reception chapter ("The most common complaints"). The descriptions are also given for each vehicle model in the model-specific information chapters.
Odor from air conditioning The complaint "Damp air or odor of laundry just after engine start" is due to physical laws. Fluid that accumulates at the evaporator during operation is absorbed by the air in the evaporator housing when the blower is shut off. When the blower is activated again, this damp air is carried into the interior compartment within the first few minutes. Repairing or replacing components does not remedy the problem. This should be explained to the customer. In the event of odor-related complaints, make sure that there are no objects or dirt in the vehicle that might be causing the odors (luggage compartment, under the seats and floor mats, ashtray, stowage compartments). Furthermore, when air recirculation is active, odors from dirt on shoes or floor mats may be drawn in and circulated in the interior compartment by the blower. Refer to the "A/C Check" to identify the source of the odor. In this context also refer to the note "Automatic air recirculation". Sporadic odors may be caused by temporary environmental influences such as exhaust gases from other vehicles, tunnels, agriculture etc. Fogged windows Possible causes for windows fogged on the inside may be: • Damp in the interior (check floor mats and carpeting) • Dirty windows promote window fogging so it is important to keep the windows clean (inside and outside). • Driving with air conditioning deactivated (explain to the customer that this does not save fuel because the air conditioning systems in current model series feature volume-controlled refrigerant compressors) • Badly set air outlets/flaps (particularly the center air outlets, side air outlets, and defroster outlets). The air flow should be directed onto the fogged areas (see FlashFog logic). • Fouled filters • Driving with air recirculation activated (exacerbated by having the air conditioning off) • Refrigerant compressor shutoff (engine emergency off, anti-icing protection, consumer shutoff) • Due to the "Evaporator drying" function (further information can be found in the "Evaporator drying" function description), the inner windows may become fogged within a period of 1-3 hours of the engine being shut off. In this case, the outside temperature threshold value can be coded to a higher temperature (e.g. 14 °C) on vehicles of model series 204 (as of YoM10) and 207/212 (as of YoM11). Vehicles from before the corresponding modification year can also be equipped with the new SW release. Possible causes for windows fogged on the outside may be: • Positions of center air outlets (diffuse field) or other flap positions. The air flow should be directed away from the fogged areas.
Vehicle Climate Control - Troubleshooting-Function-Design-Operation - Current Passenger Car Models b
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Climate control information in detail (Climate control complaints)
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Climate control information in detail (Climate control complaints)
Windows fogged on inside/refrigerant compressor nonfunctional (model series 164/ 251) The refrigerant compressor switches off at temperatures below 3 °C to protect itself. If, after the refrigerant compressor has switched off, the ambient temperature increases or the driver drives into an area with an outside temperature > 0 °C, the refrigerant compressor only switches on if the temperature of the engine coolant is < 40 °C or the vehicle speed is > 45 km/h. Inform the customer that the system cannot be operated in air recirculation mode in such cases and that the DEFROST button should be activated. Odors produced by PTC heater booster (model series 211/219) The SAM control unit (N10/1) may be responsible for this complaint if it does not actuate the heat exchanger shutoff motor (M16/32) during operation. Saving fuel by driving with the air conditioning deactivated All current vehicle model series are fitted with volumecontrolled refrigerant compressors (with and without magnetic clutch). These refrigerant compressors are tuned for optimum fuel economy because they are only ever actuated according to requirements. This is not visible from the outside. Therefore, switching off the air conditioning when outside temperatures are low has only a very slight influence on fuel economy, but can encourage fogged windows or odors from the evaporator. Advise the customer to leave the air conditioning switched on all the time. Differences between "identical" vehicles Due to the variety of different versions and new features introduced in the course of each year, differences in the control logic are highly probable. Furthermore, the codings may vary, meaning that fundamentally different control logic systems are involved. For this reason we strongly discourage the use of reference vehicles. This should also be pointed out to the customer if necessary. Differences in new vehicles of existing owners Existing customers with new vehicles should be advised that the functions of the air conditioning can change with every modification year. It is therefore highly likely that functions with which the customer was familiar from his old car have changed in his new vehicle. This should be explained to the customer when selling the vehicle or when complaints are received! Faults do not usually exist with this kind of complaint. Differences of "DEFROST" function" Depending on the vehicle model, the powerplant and the modification year in question, there may be differences in the control/actuation of the blower when "DEFROST" is activated. What is more, differences in control are possible in the same vehicle because, depending on the engine heat output, the ambient conditions and other influencing factors, the best possible control curve can be selected in order to deice the windows as quickly as possible.
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Control differences Reactions to changes in the target temperature on the operating unit may vary considerably from vehicle to vehicle depending on the engine heat output, the ambient conditions and other influencing factors. In each case the control unit selects an optimized control curve to achieve the best possible adaptation. For example, it is possible to change only the outlet temperature of the air without changing the blower stage. Similarly, open windows, doors and sliding roof or Vario roof can cause differences in the control of the air conditioning in certain vehicles. Reaction time of air conditioning Air conditioning systems require a certain amount of time to regulate the set temperature. Give the air conditioning time to stabilize properly. A drastic manual increase or reduction in the temperature or blower stage (e.g. when starting up and in extreme outside temperatures) does not normally produce quicker reactions. Implausible regulation – single/multiple-zone sun sensor Multiple-zone sun sensors have a substantial influence on temperature control. When the sunlight hits the vehicle at an angle, this may result in extreme differences in the outlet air temperatures and blower outputs between the left and right sides. This effect can also occur under cloudy skies due to UV radiation. The sensitivity of the sun sensor can be coded with Xentry Diagnostics (XD)/Xentry DAS.
Implausible regulation – outside temperature indicator temperature sensor If you cannot understand why the climate control is operating in a certain way, the outside temperature indicator temperature sensor (B14) should also be taken into account. Through a simple plausibility check (e.g. comparison of outside temperature value shown on instrument cluster) while driving when the complaint occurs, it is possible to rule out the possibility that the control unit of the air conditioning is receiving an incorrect outside temperature value and thus regulating incorrectly. Weather-related effects (e.g. due to snow and ice) or mechanical impairment (e.g. a sensor unclipped by a foreign object) must also be considered. You should also take the information in the model series-specific "Climate control functions" section under the "Outside temperature" point into account. Implausible regulation on model series with several interior temperature sensors In the event of implausible regulation or nonfunctional components: check interior temperature sensors present. Temperature differences Temperature differences between the driver and front passenger side are normal in certain model series and should be compensated for by regulating the operating unit manually.
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Climate control information in detail (Climate control complaints)
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Climate control information in detail (Climate control complaints)
Temperature differences between left and right Warning for air-regulated systems: In the event of temperature differences between left/right do not replace the shutoff valve. Separate valves (pulsed valves) for the left and right sides exist only in waterregulated systems. Poor control quality/temperature differences/ intermittently too hot or too cold/cold feeling The customer complaint "poor control quality/ temperature differences/intermittently too hot or too cold/cold feeling" may be caused by leakage in the bodywork. This applies above all when the complaint occurs in conjunction with abrupt vehicle speed changes (e.g. braking after driving fast). In order to provide the engine with the required power at very high speeds or acceleration, the output of the refrigerant compressor can be reduced. This can cause the complaint "Blower output too warm". This is normal and does not justify replacing parts. Temperature differences/blower output occasionally too warm (hybrid vehicles) The customer complaint "Temperature differences/ blower output occasionally too warm" can be due to temporary limitation of the output of the electric refrigerant compressor. Please note that output limitation of the electric refrigerant compressor does not cause a fault memory entry because it is a normal and necessary protection function of the battery management system. Replacing parts does not remedy the problem. Refer to the note "Consumer shutoff". Cold feeling after driving for a long time The customer complaint "cold feeling after driving for a long time" is usually due to subjective sensations or settings on the air conditioning. The cause of the customer complaint "cold feeling after driving for a long time" is a natural reaction of the body, which adopts a state of rest after long periods without physical exertion and produces less heat. Since freedom of movement is severely restricted inside the vehicle, the blood flow in the legs especially is impaired. The result is inadequate blood circulation, which can lead to a "cold feeling" in the legs. If the customer complains of a "cold feeling after driving for a long time", advise them to adjust the temperature of the air conditioning manually to suit their needs and on long journeys to take regular breaks with physical exercises (rule of thumb:every 200 kilometers or every two hours). Also check the settings for the rear blower (cold air in the rear compartment can travel into the front footwells.) "Cold feet" (with code 582 Rear air conditioning) If the customer complains of "cold feet", first check the settings in the rear compartment. If the rear is set to "cooling", it can happen that the cold air travels forwards from the rear under the seats.
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No or poor heat output Depending on the engine model installed, this may be caused by the heating system shutoff valve (Y16/2) at the engine. This valve is controlled via the engine control unit. Please check accordingly. Poor heat output/cooling output in rear The control response in the rear can be delayed because the air or hot water (with code 582 Rear air conditioning) has to travel a longer distance from the front air conditioner housing or engine to the rear air vents and can thus cool down or heat up on the way. Poor heat output/cooling output in rear (model series 164/251) The climate control system reacts with a delay in the rear compartment because the first seat row is given priority. Cold feeling at the rear/no heating at the rear (without code 582) The rear center air outlet always takes its air from the coolest point. For this reason cool air emerges from the rear center air outlet even when heating mode is active at the front. In the case of this complaint it is advisable to close the rear center air outlet. Warmer air is then supplied via the rear footwell air outlets and also via the B-pillar on model 221. Replacing parts does not remedy the problem.
Rear air conditioning nonfunctional (all model series with code 582) Check and, if necessary, replace the rear refrigeration circuit shutoff valve (Y67). The filter may be clogged. When removed, visually inspect for shavings and dirt. Heats constantly at rear – defective shutoff motor (model series 211) The complaint "air conditioning heats constantly at the rear" may be caused by a defective heat exchanger shutoff motor (M16/32) (see GI83.40-P-020954). Knocking noises from pulsed valves Knocking noises in model series with water-regulated air conditioning systems (see chapter "Knowledge base") are normal. The noises are caused by the pulsed valves. In residual heat mode these noises are more obvious because they are normally overlaid by other noise sources while driving. Replacing parts does not remedy the problem. Gurgling noises (model series 171) Air in the cooling-water circuit can cause gurgling noises. The problem can be remedied by evacuating the system by vacuum and then refilling the coolingwater circuit at 1.4 bar. Then allow the engine to warm up at a pressure of 1.4 bar.
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Climate control information in detail (Climate control complaints)
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Climate control information in detail (Climate control complaints)
Sound level of electric refrigerant compressor (hybrid vehicles) Due to the low engine sound level and automatic engine stops, isolated customer complaints are received about the sound level of the electric refrigerant compressor. Up to a refrigerant compressor speed of approx. 3000 rpm, the sound level is perceived as a "non-distracting buzzing sound" but above this speed the sound level is somewhat higher and audible from the outside. If the electric refrigerant compressor is producing a different sound level, the refrigerant compressor may not be supplying its full output during control operations. By checking the condition (coloration, residues from mechanical wear) of the refrigerant and refrigeration oil, it is possible to rule out the possibility that the electric refrigerant compressor is mechanically damaged and thus causing excessive noise. Replacing parts without prior inspection will not rectify the problem. Flow noises/whistling noises in the interior at high vehicle speeds (model series 216/221) At higher speeds and with the flaps in certain positions, there may be turbulence in the air stream which may cause flow noises. Possible remedy: code speeddependent recirculated air via Xentry Diagnostics (XD)/Xentry DAS. More air from one outlet than from others If the customer complains of "more air from one outlet than from others", note that when some air outlets are closed, the air flow is distributed among the remaining outlets in the vehicle and this can result in air flows of varying intensity. The climate control can also create such differences intentionally (e.g. to compensate for the angle of the sun). No air or insufficient air emerging although the blower is running If the blower is running but there is no air at any outlet, this can be an indication of icing in the evaporator. This symptom disappears when the vehicle and the engine are left off for a certain time (the ice at the evaporator thaws). To rule out the possibility of a defective evaporator temperature sensor (B10/6), also check the evaporator temperature sensor (B10/6) for plausibility using Xentry Diagnostics (XD)/Xentry DAS for this customer complaint. No blower setting bars on the display in "DEFROST" or "REST" mode Depending on the model year, when the "DEFROST" or "REST" function is activated the blower setting bars on the display disappear and a fixed blower setting and temperature are set. As long as this function is active, the customer will not be able to intervene in the control process.
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ACOFF or A/C button lit/flashing constantly or ACOFF A/C button nonfunctional The complaint "no cooling output or ACOFF or A/C button lit/flashing constantly" indicates that the air conditioning system is empty or not sufficiently full. The refrigerant compressor has been shut off for its own protection. The detailed procedure can be found in WIS under "Empty/evacuate/refill air conditioning and check for proper operation and leaks". "AC-OFF" in central climate control menu on the COMAND display cannot be deactivated (model series 216/221) The complaint "AC-OFF in central climate control menu on the COMAND display (A40/8) or on the SPLITVIEW display (A40/10) (with code 867) cannot be deactivated" indicates that the air conditioning system is empty or not sufficiently full. The refrigerant compressor has been shut off for its own protection. The detailed procedure can be found in WIS under "Empty/evacuate/refill air conditioning and check for proper operation and leaks" (AR83.30-P-1760SX). Air conditioning does not cool (old model series up to model series 211/219) An important change in the operation of air conditioning systems (control logic) is the assignment of the "A/C" or "ACOFF" button. Please be sure to point this out to the customer. The air conditioning is cooling or the refrigerant compressor is operating - when the "A/C button" is lit or - the "ACOFF button" is off. When replacing operating units in particular, please note that there may be differences in the control logic and expressly advise the customer of this. Before replacing an operating unit, always perform a circuit 30 reset in order to check the function.
Air conditioning switches on automatically (hybrid vehicles) When the high-voltage battery module requires cooling, the battery management control unit issues a cooling request. This can result in the electric refrigerant compressor starting up audibly e.g. with the start/stop function active. The air conditioning operates with the same settings prior to it being switched off. Air conditioning cannot be switched off (hybrid vehicles) If the high-voltage battery module still requires cooling, the air conditioning cannot be shut off (disable function: the deactivation is reversed after 2 battery is cooled. Noises after switching off If the customer complains about "whistling or hissing noises after switching off", point out that these can be produced by the equalization of gas pressure at the expansion valve. These noises can even occur a long time after the vehicle is switched off. Other noises after switching off can be caused by actuator motors moving into their park position (as much as several minutes after switching off the ignition). Replacing parts does not remedy the problem.
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Climate control information in detail (Climate control complaints)
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Climate control information in detail (Climate control complaints)
P1664 Unit fault — electric water heater (model series 203/209) Fault message in instrument cluster with fault entry P1664 "Unit fault" in engine control unit If there is no customer complaint about the heater booster function, the fault can be ignored and erased. In each case the electrical contacts should be checked for the sake of safety. Malfunction: Heating instead of cooling and vice versa (model series 209) The interior sensor coding or the 2nd interior sensor in the overhead control panel is transmitting incorrect signals. Check the interior temperature sensor in the overhead control panel. Cold air after stationary heater operation and/or residual heat mode (model series 211/219) The SAM control unit (N10/1) may be responsible for this complaint if it does not actuate the heat exchanger shutoff motor (M16/32) during operation.
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The following pages contain important information and background knowledge about climate control functions.
Automatic air recirculation Automatic air recirculation is not indicated by the function LED. Depending on the equipment installed, automatic air recirculation is activated e.g. in the case of high outside temperatures or poor quality of the fresh air (pollutants). Automatic air recirculation is not possible when the following settings are active: • Air conditioning deactivated (note control logic of A/C – ACOFF buttons) • Maximum heating • DEFROST • In vehicles with activated charcoal filter button on the operating unit. If there are pollutants in the air, automatic air recirculation is only possible when the activated charcoal function is activated using the activated charcoal filter button on the operating unit (see chapter "Knowledge base") • In cold temperatures (only at temperatures above approx. 5 °C, even if the activated charcoal filter is activated) The sensitivity of the pollutant sensor changes according to the ambient conditions. For this reason, exhaust odors after driving for a long time under identical environmental conditions may be normal. Air recirculation flap closes when air conditioning is switched off When the air conditioning is switched off using the "0 button" or the blower is set to "0" (depending on equipment installed), the air recirculation flap is closed. The function can be set via Xentry Diagnostics (XD)/Xentry DAS. Reduction of door closing forces through flap adjustment When the ignition is off and one of the doors is opened, the fresh air/recirculated air flap and the ram air flap (with code 581) are partially opened by the fresh air/recirculated air/ram air flap actuator motor. This reduces the door closing forces. The function can be set via Xentry Diagnostics (XD)/Xentry DAS. Convenience closing Convenience closing (tunnel mode switching) is only possible provided that all the windows and the tilting/ sliding roof (if installed) are normalized. If necessary, normalize the components with Xentry Diagnostics (XD)/Xentry DAS. If the air recirculation mode button is pressed briefly after convenience closing has occurred, the previously stored positions (windows, sliding roof) are lost. In vehicles fitted with activated charcoal filter button, this can also be used to operate the convenience closing feature. For a detailed description of the "convenience closing" function, refer to the explanation of the "air recirculation mode button" in the relevant model description. Speed-dependent ram air mode To prevent the air feed into the interior compartment from increasing as the vehicle speed increases, the fresh air/recirculated air flap (with code 580) and the ram air flap (with code 581) are adjusted on a speeddependent basis. The higher the speed, the further the ram air flap is closed.
Vehicle Climate Control - Troubleshooting-Function-Design-Operation - Current Passenger Car Models b
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Climate control information in detail (Climate control functions)
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Climate control information in detail (Climate control functions)
FlashFog logic To prevent windows from fogging up, no air is directed at the windshield for a short time after engine start. This function cannot be prevented even by adjusting the flaps manually. Only the defrost function disables the FlashFog feature. The duration of this function can vary depending on the model series and the ambient conditions. In the event of complaints, this should be explained to the customer. Defrost function When the Defrost function is activated, the refrigerant compressor is actuated to dry the air as effectively as possible. Anti-icing protection To prevent the refrigerant compressor from icing up, the values from the evaporator sensor are checked constantly while the air conditioning is operating. If the values approach the 0 °C limit, the control unit turns down the refrigerant compressor in order to prevent icing. This produces temperature fluctuations/surges at the evaporator sensor which may be perceived by sensitive customers. Please note that the anti-icing protection of the refrigerant compressor does not cause a fault memory entry because it is a normal and necessary protection function of the air conditioning system. Replacing parts does not remedy the problem. Evaporator drying (as of model series 204) In order to counteract odors from the evaporator in the interior compartment and prevent fogging of the windows when the air conditioning starts up, the evaporator of the air conditioning system is dried. One hour after the engine is shut off, the instrument cluster transmits the request to dry the evaporator to the AAC [KLA] control and operating unit via interior CAN, which initiates drying of the evaporator. To do so, the blower is activated at its lowest stage for 30 min. This coding is coded to "active" or "not active" at the plant depending on the model series and country of sale. Cold start lockout The cold start lockout function prevents a high blower speed from being set in cold outside temperatures. This function is purely for the customer's comfort. As the temperatures in the heating circuit rise, the blower speed setting is increased.
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Center air outlet In cold outside temperatures or in heating mode the center air outlet can be closed automatically by the air conditioning control unit in order to improve comfort levels. Because warm air rises, this results in more uniform heating of the interior compartment. Diffuser outlet (model series 211/219) As of 04/07, diffuser outlets are no longer installed on model series 211. Air ducting (model series 221/216) On model series 221/216, the air distribution can be changed either using the buttons in the upper control panel or electronically via the central display. Cold air reduction (model series 211/219) If installed, the cold air reduction feature (see model description for an explanation) can be used in heating mode to direct cooler air to the center air outlet than is set on the operating unit. In model series 211 the cold air reduction function is deactivated in AUTO mode. Warm air increase (model series 230) The warm air increase feature (if installed; see chapter "Knowledge base" for an explanation) opens the center air outlet in heating mode. The temperature of the emerging air is regulated according to the target temperature selected on the operating unit.
Blower lowering via voice control system (VCS) (as of model series 204) With the voice control system active, the blower output is limited to 50%. To do so, the radio and navigation unit or the COMAND controller unit transmits the status of the voice control system to the automatic air conditioning control and operating unit via interior CAN. This then limits the blower output. Blower lowering via voice control system (VCS) (model series 169/245) (as of 1.6.09) When the voice control system is active on vehicles with code (581) Comfort automatic air conditioning as of 1.6.09, the blower output is limited to 25%. To do so, the radio and navigation unit or the COMAND controller unit transmits the status of the voice control system to the automatic air conditioning control and operating unit via interior CAN. This then limits the blower output. Reduction of blower output with ECO start/stop system When the blower for automatic air conditioning is active, the blower output is reduced. At warm ambient temperatures, the system switches to air recirculation mode depending on the specified temperature setting.
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Climate control information in detail (Climate control functions)
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Climate control information in detail (Climate control functions)
Consumer shutoff Most Mercedes-Benz vehicles feature a consumer shutoff function. If the on-board power supply voltage is too low, e.g. when several consumers are switched on just after moving off or when the engine is idling, certain convenience functions may be stepped down or shut off entirely. These functions include the vehicle climate control, the "residual heat" blower control (can also be shut off while stationary) and the stationary heater or heater booster (PTC). Although an increase in the blower stage can be seen on the display in the case of a temporary consumer shutoff, the blower itself does not react. Likewise it is possible that the rear window heater may not start up even though it has been activated and activation is confirmed by the lighting of the function LED on the operating unit. A fault is not stored in the case of a temporary consumer shutoff. When these complaints are encountered, it is therefore absolutely essential to find out the precise ambient and driving conditions that existed at the time the complaint occurred. Actuation of rear window heater In all model series apart from model series 164/251, the rear window heater is regulated by the rear SAM and not by the AC operating unit. However, in all models the rear SAM receives and passes on the "rear window heater" signal (including model series 164/ 251). For this reason, it is absolutely essential to check the rear SAM component as well in the case of a malfunction of the rear window. Switch-on time of rear window heater After the rear window heater button is actuated, the rear window heater is generally switched on immediately and its operation is confirmed by light-emitting diode (LED) in the button. However, if there is a temporary on-board electrical system undervoltage (less than 5 min), the LED may light up even though the rear window heater is shut off. Refer to the note "Consumer shutoff". The duty cycle (automatic shutoff) of the rear window heater depends on the outside temperature and vehicle speed. These control features are intentional. Please explain this logic to the customer. Replacing parts does not remedy the problem. Key-dependent storage of air conditioning settings (model series 211/219) Dependent on the equipment variant of the air conditioning system and the vehicle model, key-dependent air conditioning settings can be saved (memory function). In other words, different settings for the air conditioning can be saved according to which transmitter key is used. Refrigerant compressor actuation (model series 169/245, 216/221) The refrigerant compressor is actuated not via SAM, but directly by the air conditioning control unit.
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Actuation of electric refrigerant compressor (hybrid vehicles) The electric refrigerant compressor is not actuated directly by the AAC [KLA] control unit and can be actuated by two different events: • Interior climate control request: The AAC [KLA] control unit transmits a cooling request via interior CAN (CAN B) to the central gateway (CGW) control unit. This routes the request via chassis CAN (CAN E) to the ME-SFI [ME] control unit. The ME-SFI [ME] control unit then actuates the electric refrigerant compressor via the drive train sensor CAN (CAN I). • High-voltage battery module cooling request: The battery management control unit transmits a cooling request via ME-SFI [ME] and CGW to the AAC [KLA] control and operating unit. Please refer to the data flow charts and block diagrams in the relevant model descriptions. Air conditioning starts up with a delay Under certain circumstances, temperature changes when the vehicle is parked (e.g. day/night differences) may cause the refrigerant compressor to start up with a delay when the engine is started. This is due to natural causes. Repairing or replacing components does not remedy the problem.
Refrigerant compressor startup condition (model series 164/251) In model series 164/251 the outside temperature value is one startup condition for the refrigerant compressor. With rising outside temperatures and vehicle speeds below 30 km/h, the colder value is retained. This can be one reason for the air conditioner failing to start up at cold outside temperatures after the vehicle is moved into a warmer environment (e.g. workshop, underground garage). No "click" when switching on the air conditioning All current Mercedes-Benz model series are fitted with volume-controlled refrigerant compressors with and without magnetic clutch depending on the variant. The typical "click" when a refrigerant compressor without magnetic clutch starts up no longer occurs. It is no longer possible to hear the refrigerant compressor switching on. On refrigerant compressors with magnetic clutch, their activation can be heard by a quiet "click". Note that the switch-on and switch-off points may be delayed. In case of doubt, make sure that the shaft on the refrigerant compressor is turning when the engine is switched on.
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Climate control information in detail (Climate control functions)
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Climate control information in detail (Climate control functions)
ACOFF in central display (model series 221/216) On model series 221/216 there is, for the first time, no switch in the upper control panel for activating/ deactivating the refrigerant compressor. The system is activated/deactivated electronically via the central display. Outside temperature value Outside temperature indicator temperature sensor (B14): The outside temperature value is stored as soon as the vehicle travels slower than 30 km/h. This value is adjusted in stages only when the vehicle travels faster than 30 km/h for a certain length of time. When the vehicle is stationary, therefore, a plausibility check of this sensor value using Xentry Diagnostics (XD)/Xentry DAS is not meaningful because only the stored value for the outside temperature can be retrieved. There is no possibility to reset the stored outside temperature value. Should you encounter complaints concerning the temperature control which cannot be reproduced while stationary, we recommend that you attempt to reproduce the complaint under the conditions described by the customer (see reception protocol). Electric heater booster (model series 203) On model 203 with diesel engine, the electric heater booster is installed in the engine (block heater with 1.8 kW). PTC operation with refrigerant compressor switched off The PTC heater booster is coded at the plant to operate irrespective of the position of the A/C button (refrigerant compressor on/off). This ensures that the heater booster function is available even with the refrigerant compressor switched off e.g. in winter. The coding can (except on model series 203) be changed via Xentry Diagnostics (XD)/Xentry DAS. If an electric heater booster is installed on model series 203, it can be programmed in the instrument cluster on certain variants for operation with the refrigerant compressor switched off. Programming the heater booster via Xentry Diagnostics (XD)/Xentry DAS is not possible on model series 203. Switch on/off conditions of PTC heater booster (model series 211/219) ACOFF button on vehicles up to 11/04: With the ACOFF button activated, the PTC heater booster is switched off. Vehicles as of 11/04: PTC heater booster is no longer switched off/affected by the ACOFF button. Consumer shutoff: If consumer shutoff stage 1 or 2 is active, actuation of the PTC heater booster is disabled. Remedy: higher engine speeds. On-board electrical system: If several consumers of the on-board electrical system are switched on simultaneously (e.g. driving lights, audio system, rear window heater and seat heaters), the output of the alternator is not sufficient to ensure proper operation of the PTC heater booster. Remedy: higher engine speeds.
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b Vehicle Climate Control - Troubleshooting-Function-Design-Operation - Current Passenger Car Models
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Booster blower (model series 203) In model series 203 with code 581 an additional blower motor (booster blower) may be installed in the rear compartment of the vehicle. When the blower is installed, there is an additional potentiometer on the rear center air outlet selector wheel. Visually there is no discernible difference in the installed condition. For details on identification refer to the component description for the rear blower motor. Rear blower actuation (model series 204, 207, 212) To prevent excessive noise from high blower speeds, actuation of the rear blower while driving is limited to max. 3500 rpm (70%). A speed of 5000 rpm can be reached via actuation with Xentry Diagnostics/Xentry DAS. Rear air conditioning systems (with code 582) Rear air conditioning systems only draw in interior air (please note this in the event of odor-related complaints). Rear operating unit resets settings (model series 164/251) In model series 164/251 the custom rear compartment settings are erased and reset to 22 °C and automatic mode after approx. 30 minutes with the ignition switched off. This is intentional. Replacing components does not remedy the problem.
Rear operating unit display A blower stage bar is displayed on the rear operating unit despite the blower being inactive. Model series 171 without air conditioning In some countries, model series 171 with M271 is not fitted with an air conditioning system in the basic variant as standard equipment. Omission of second heat exchanger with code 582 (model series 251) Shortly after production start-up, the second heat exchanger in the rear was omitted from model series 251 with code 582 and along with it the additional heat output for the third seat row. AUTO mode on model series 169/245 with code 580 Some of the flaps are adjusted via Bowden cables, in which case no automatic flap control is possible. Day/night representation (model series 215/220) The day/night representation in the AC operating unit when the lights are turned on/off is only available up to 06/2001.
Vehicle Climate Control - Troubleshooting-Function-Design-Operation - Current Passenger Car Models b
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2.1/15
Workshop
Climate control information in detail (Climate control functions)
Workshop
Climate control information in detail (Climate control repairs)
The following pages contain important information and background knowledge about repairing air conditioning systems.
Work on vehicles with high-voltage on-board electrical system (hybrid vehicles) Personnel who perform repair, maintenance and diagnosis activities on vehicles with high-voltage on-board electrical systems must have completed a special course of qualification. (awareness course for highvoltage on-board electrical systems). A special electrical qualification and authorization are essential for personnel who de-energize the highvoltage on-board electrical system before work on vehicles with a high-voltage on-board electrical system and perform the subsequent initial startup process. Persons who have not completed a special qualification course and have neither special electrical training nor authorization may not carry out work on highvoltage on-board electrical systems. Work on the refrigeration circuit Even among vehicles of the same model series the AC lines installed may be of different diameters. When carrying out repairs, make sure that the correct tool sizes (e.g. service valves) are used. Maintenance/repair work on the refrigeration circuit When carrying out maintenance/repair work on the refrigeration circuit, make sure that the system is not opened for longer than 15 minutes. In all other cases please use the specified couplings and stop plugs to keep the circuit closed (see AH83.30-N-0005-01A). Replacement of refrigeration circuit components WIS contains a detailing listing of filling capacities and the amounts of oil to be added to the refrigeration circuit for a complete refill when components are replaced (see BF83.00-Z-9999AZ). Refrigerant compressor replacement When replacing a refrigerant compressor, always make sure that metal shavings and other foreign particles are not left behind in the refrigerant circuit as these may cause renewed problems with the new refrigerant compressor (see AR83.30-P-1782A). Refrigerant compressor limiter The limiter (torque limiter) on the refrigerant compressor performs a protection function. The limiter is designed to break in order to guarantee the continued functioning of the belt drive if the refrigerant compressor seizes, for example. Check whether the shaft of the refrigerant compressor is turning (see chapter "Knowledge base" for an explanation).
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b Vehicle Climate Control - Troubleshooting-Function-Design-Operation - Current Passenger Car Models
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Belt pulley repair kit (only for older model series up to 211/219, 164/251) A repair kit for the belt pulley is available for numerous model series and engines. Refer to GI83.55-P-045067. Compressor damage Actuating the refrigerant compressor when the system has been evacuated causes serious defects. The compressor is not lubricated and is worn out. Refrigerant compressor nonfunctional/presumably defective (hybrid vehicles) Since the electric refrigerant compressor is supplied with power by the high-voltage on-board electrical system and does not have its own fault memory, all fault memory entries of the engine control unit and battery management control unit must be processed as per Xentry Diagnostics (XD)/Xentry DAS in the event of function complaints. Another basic requirement is a fully operational power supply to the electric refrigerant compressor. As a result, all electrical lines, connectors and ground points must be checked for damage and corrosion. Also refer to the information about "Working on vehicles with high-voltage on-board electrical system".
Implausible pressures at the high and low-pressure side Feel the entire line system and look for noticeable temperature differences, a sign of clogged lines. Air conditioning nonfunctional Sensors and actuators networked over the AC bus (e.g. the sun sensor or stepper motors) can disable the function of the entire AC bus if they develop a fault. Diagnostic mode In most model series the air recirculation button flashes in diagnostic mode (not to be confused with shutoff due to lack of refrigerant). This is not a fault, it indicates diagnostic mode with Xentry Diagnostics (XD)/Xentry DAS is connected. In model series 169/ 245 the diagnostic mode is not displayed. Bus faults When bus faults are detected by Xentry Diagnostics (XD)/Xentry DAS, the system must be activated without sensors and the component causing the problem must be found by reconnecting the components individually. All fault codes must be erased before each new test.
Vehicle Climate Control - Troubleshooting-Function-Design-Operation - Current Passenger Car Models b
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2.1/17
Workshop
Climate control information in detail (Climate control repairs)
Workshop
Climate control information in detail (Climate control repairs)
Erasing AC bus faults Some faults on the AC bus are only erased after ignition OFF. (For an overview of the AC bus, see System overview/block diagram). LIN bus On vehicles with LIN bus communication (see chapter "Knowledge base") note the following: Components that communicate with each other via LIN bus are switched one behind the other in series. If a sensor or actuator is defective, all the components connected downstream of it no longer function because they can no longer be actuated, or they switch to limp-home mode. Limp-home can also be actuated if the blower regulator detects a disruption in communications. If the ground connection is defective or there is a short circuit in a LIN bus component, a fault code may be stored for all the components connected to the bus. In the event of a defect or malfunction on the LIN bus, check all the components connected to the LIN bus in their proper sequence before replacing individual parts. Refer to the block diagram. Failure of the LIN bus A short to ground or short circuit in the LIN bus results in a total failure of the LIN bus. In the event of a total failure or malfunction on the LIN bus, check whether water damage has caused the failure of the air distribution actuator motors in the Bpillar. Coding The function of the air conditioning may also be influenced by codings in control units outside the air conditioning system (e.g. SAM, EZS, engine control unit, battery management control unit etc.). All control units are SCN-coded and thus preset/fused at the plant. Modifications cannot be made manually or must only be carried out after consultation with the respective MPC. Please refer to the data flow charts and block diagrams in the relevant model descriptions. Blower actuation in event of undervoltage (consumer shutoff) In the event of undervoltage, actuation of the blower is limited without a fault entry being made, mainly with the engine off (lower limit is 50% of blower output). Blower motor or blower regulator In the event of problems with the blower motor or blower regulator, check the parts one by one to ascertain which of the components is actually defective.
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b Vehicle Climate Control - Troubleshooting-Function-Design-Operation - Current Passenger Car Models
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Malfunction of LEDs on temperature selector wheels/temperature adjustment on AC control panel does not function properly or does not function at all (model series 164/251) 1 LEDs hang: Temperature adjustment on AC control panel does not function properly or does not function at all/LEDs do not change when temperature selector wheel is turned. Cause: software of AC control panel. The software for the AC control panel on the Star Diagnosis DVD as of 01/2007 solves this complaint. Flash the AC control panel with the latest software release using Star Diagnosis (later than DVD 01/2007). 2 LEDs on both temperature selector wheels flash. Cause: The additional heating water pump was coded to "inactive". Code additional heating water pump to "active" using Star Diagnosis. Control units — A/C — Automatic air conditioning — Control unit adaptations — Read coding and change if necessary — Others — Additional heating water pump. LED on right temperature selector wheel flashes. Cause: Faulty blown air sensor(s) in air ducting. If a fault is entered during the quick test, check the respective blown air sensor for correct contact and function. If no fault is entered during the quick test, check all blown air sensors for correct contact and function.
Operating unit replacement If replacement of the operating unit is unavoidable, please be sure to order the correct replacement part. Note any changes in the control and regulation logic. Check the codings before replacing the unit. When replacing operating units in particular, please note that there may be differences in the control logic and expressly advise the customer of this. Before replacing an operating unit, always perform a circuit 30 reset in order to check the function. Rear operating units Strictly speaking, rear operating units in vehicles with code 581 are merely switches and display elements with no control logic, which forward the signals to the front air conditioning control unit or display them. Replacement does not provide a remedy for problems with temperature adjustment or air ducting (exception: button or contact faults). Rear operating unit is separate control unit (all model series with code 582) On vehicles with rear air conditioning with code 582, the rear operating unit is a separate control unit which is responsible for controlling and actuating the rear air conditioning. Wiring of actuator motors on air conditioning with code 580 (model series 169/245) On model series 169/245 with SA code 580, an air recirculation flap DC actuator motor was installed. This actuator motor is actuated directly from the AC control panel via two pins. The blend air flap actuator motor is a LIN motor with four pins.
Vehicle Climate Control - Troubleshooting-Function-Design-Operation - Current Passenger Car Models b
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2.1/19
Workshop
Climate control information in detail (Climate control repairs)
Workshop
Stationary heater information in detail
The following pages contain important information and background knowledge about stationary heaters.
Stationary heater ex plant since 1.1.2011 (model series 204) On model series 204, the stationary heater special equipment has been offered since 1.1.2011. Previously, the stationary heater special equipment was not available ex plant. Stationary heater nonfunctional — Consumer shutoff The event "Consumer shutoff" in the battery control unit prevents the stationary heater from being activated in the event of undervoltage in the on-board electrical system or causes it to shut off. If consumer shutoff is active or stored in the control unit, the onboard electrical system and/or the on-board power supply voltage/vehicle battery(-ies) must be checked. Stationary heater nonfunctional – Consumer shutoff due to short-distance operation The battery cannot reach its optimum charge level if the vehicle is driven over short distances at a low engine speed with high current consumers frequently switched on (e.g. heated rear window, heated seats etc.). Rule of thumb: Heating time = Driving time. Battery control unit switch-off threshold (model series 164/251) On vehicles with gasoline engine, the switch-off threshold of the battery control unit can be programmed to 11 V. The switch-off signal of the battery control unit can be deactivated by programming. Stationary heater nonfunctional – defective LED A defective LED in the stationary heater switch on the control panel prevents the stationary heater from operating, the stationary heater switch is defective. The fault 'LED defective' is stored in the stationary heater control unit. Stationary heater nonfunctional – empty tank To ensure that the stationary heater operates properly, the vehicle tank must be at least ¼ full and the vehicle should be parked almost horizontally to ensure optimal fuel intake. Stationary heater nonfunctional – fault interlock After 3-6 failed start attempts (model series-dependent), the heater unit is disabled. The stationary heater can only be reactivated after it is enabled using Xentry Diagnostics (XD)/Xentry DAS. Stationary heater nonfunctional – crash safety shutoff In the event of a crash, the stationary heater or heater booster function is permanently switched off. The interlock can only be released via Xentry Diagnostics (XD)/Xentry DAS.
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b Vehicle Climate Control - Troubleshooting-Function-Design-Operation - Current Passenger Car Models
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Stationary heater nonfunctional – heater overheated Overheating protection may be activated by air in the water circuit. As a result, the water circuit must be inspected for leaks and then bled. The interlock can only be released via Xentry Diagnostics (XD)/Xentry DAS. Stationary heater nonfunctional – intake hose (model series 203) The intake hose of the stationary heater burner unit can work loose from its original position and come into contact with the fender liner. This can interrupt the fresh air supply. Also check the intake hose for any escaped damping material. This can be sucked inside in unfavorable conditions. Stationary heater nonfunctional on diesel vehicles Ensure that the fuel is suitable for winter conditions, especially in the transitional period between seasons. The fuel line can be jellified by summer diesel. Stationary heater nonfunctional, switches off or smokes after long idle period An extended period of non-use, e.g. over the summer months, can result in air bubbles in the fuel line. Several start attempts should be carried out until the stationary heater starts up. To "burn off" the heater unit, the stationary heater must then be left on for at least one entire heating cycle.
Stationary heater does not start despite program preselection (model series 216/221) Stationary heater does not start despite departure time being set (program preselection unit in central display). If a departure time is programmed in the stationary heater menu and the B-CAN then goes to sleep, the programmed data are lost when circuit 15R is switched back on. The departure time is still shown correctly in the central display. Flash the instrument cluster with the latest software. Stationary heater nonfunctional – loose fuel line (model series 220) On model series 220, a loose fuel line/hose or a kinked fuel hose can cause the stationary heater to malfunction. Perform a check and, if necessary, refasten the lines/hoses using a hose clamp. Stationary heater starts without obvious cause and/or stationary heater indicator lamp flashes (model series 215/220) This complaint can occur on vehicles with code 228 and code 352 (COMAND) in combination. Recode the instrument cluster.
Vehicle Climate Control - Troubleshooting-Function-Design-Operation - Current Passenger Car Models b
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2.1/21
Workshop
Stationary heater information in detail
Workshop
Stationary heater information in detail
Stationary heater only operates in test mode using Xentry Diagnostics (XD)/Xentry DAS Make sure that the stationary heater is coded in the CGW/EZS and that initial startup has been performed with Xentry Diagnostics (XD)/Xentry DAS. Stationary heater smokes Check the direction of rotation of the combustion air blower of the stationary heater. (If the motor connector was disconnected, e.g. during repair, polarity reversal can cause the fan to rotate in the wrong direction.) Check the exhaust pipe for damage or clogging. Check that air can exit the exhaust pipe via Xentry Diagnostics (XD)/Xentry DAS "Combustion air blower actuation". Stationary heater smokes, turns off, nonfunctional (model series 216/221) This can be caused by an incorrectly installed or kinked fuel intake line in the tank. Please check separately whether the fuel metering pump or the fuel intake system is the cause of the problem. To do so, use Xentry Diagnostics (XD)/Xentry DAS to check the fuel delivery rate with the fuel being drawn from an external receptacle (e.g. fuel canister). If the fuel delivery rate is OK, look for the cause in the fuel intake above the tank (e.g. intake fittings, line). This means that the fuel metering pump is OK. Optimized intake fittings have been installed since 03/2006. For vehicles prior to this production date with problems in the fuel supply from the tank an optimized cap (part no. A 221 470 09 41) is available. Stationary heater shuts off when engine is switched off (model series 164/251) In the context of battery management, the stationary heater is also switched off on model series 164 and 251 after the engine is switched off. This function was first introduced in series production in September 2009. Stationary heater or heater booster must be replaced. If replacement of the stationary heater or heater booster is unavoidable, be sure to use the correct part number when ordering the new part. Maximum heating and ventilation duration Depending on the default setting and ambient conditions, the maximum heating and ventilation duration of the stationary heater is 50 min. This is a default setting which can be changed via Xentry Diagnostics (XD)/Xentry DAS. As of model series 204, 207, 212, 221/216, the optimal heating duration is automatically calculated by entering the desired departure time. This also depends on: the temperature settings on the AC operating unit, the interior and outside temperature as well as the temperature of the coolant.
2.1/22
b Vehicle Climate Control - Troubleshooting-Function-Design-Operation - Current Passenger Car Models
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Logic change regarding start/departure time For the first time on model series 221, the departure time and not the start time for the stationary heater is entered in the instrument cluster/remote control. Stationary heater button – preselection time menu (model series 211/219) When the button is actuated for less than 2 s only the preselection time menu is called up – with the system switched off. The system will be activated if the button is pressed for a longer time. When the system is switched on, pressing the button immediately switches it off – without the preselection time being called up. Remote control T70/T90/T100 Remote control T90 replaces remote control T70. T90 gives the user feedback about whether the switch on/ off signal has been received. The T90 was deployed as of May/June 2004 in all model series except 203/ 209. It was deployed in model series 203/209 in November 2004 and in the Maybach in September 2004. The T100 replaces the T90. The T100 was first deployed in model series 221 as of June 2006. Stationary heater remote control nonfunctional Empty batteries or battery contact problems can impair the function of the stationary heater remote control.
Range of remote control The range and/or operation of the remote control can be influenced or impaired by a number of different factors (e.g. garage door openers, cordless telephones, transmitter masts, power lines) or obstacles (e.g. buildings). Manual teach-in of stationary heater remote control (T100) Hold down the instant heat button in the control panel until the red LED in the instant heat button starts to flash; release button; immediately press the OFF button on the remote control; the teach-in process is complete. Max. 3 remote controls can be stored. Alternatively, the teach-in process can be carried out with Xentry Diagnostics (XD)/Xentry DAS. Stationary heater remote control nonfunctional after disconnecting/connecting vehicle battery The taught-in transmitter can be lost when the vehicle battery is disconnected and then reconnected if conditions are unfavorable. Teach in the remote control again. Radio failure message "¢FAIL" (all model series with remote control T100) The message "¢FAIL" on the display of the remote control can also be caused by inadequate range or reduced range in the event of heavy interference (e.g. underground garage). Always check before replacing!
Vehicle Climate Control - Troubleshooting-Function-Design-Operation - Current Passenger Car Models b
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2.1/23
Workshop
Stationary heater information in detail
Workshop
Stationary heater information in detail
Green LED of remote control does not light up when switching off stationary heater with remote control (model series 211) Error in operating instructions, it should read "red LED lights up when switching off". Air distribution implausible during stationary heater operation The AC control panel is responsible for air distribution during heating or ventilation mode. Check complaints related to air distribution using the fault tree for climate control complaints. Clicking noises during stationary heater operation The fuel metering pump of the stationary heater can produce pulsation noises which are normal. Check the metering pump for correct seating and check the soundproofing (pump may not contact body). Heating temperature preselection/insufficient heat output when activated with preselection via instrument cluster/remote control The stationary heater heats or ventilates the interior for the set departure time depending on the outside temperature, inside temperature and the specified temperature value set on the automatic air conditioning control and operating unit (N22/7). Thermo Top V (model series 164/251) As of September 2006, Thermo Top V stationary heaters from Webasto have been installed in model series 164/251. Retrofitted stationary heater This guide only deals with stationary heaters that are installed in the vehicle at the plant (identifiable via SA code 228). The advice contained in this guide may help to troubleshoot retrofitted systems but has only been tested on systems installed ex plant. For questions regarding complaints about retrofitted variants, contact your relevant LC or the manufacturer Webasto at the hotline number +49 (0)1805-932278. Mon-Fri 8 a.m. – 6 p.m. Stationary heater run-on If the combustion air blower of the stationary heater is in the run-on phase, the stationary heater cannot be activated even though the LED is on. Run-on of fossil fuel heater booster The fossil fuel heater booster continues to run for a period when switched off. This function burns off the fuel remaining in the device and the heater booster is also cooled by the internal blower run-on after the combustion process finishes. Poor heat output after cold start with OM642 (model series 216/221) As of modification year 01/2007, fossil fuel heater boosters are no longer installed on OM642 as standard. To provide sufficient heat output after a cold start, the engine operates in heating/combustion mode during this period.
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b Vehicle Climate Control - Troubleshooting-Function-Design-Operation - Current Passenger Car Models
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PTC heater booster (model series 216/221) On model 221 with diesel engine, the PTC heater boosters are installed in the heat exchanger. Stationary heater repair method On many stationary heaters (Thermo Top C), it is possible to replace the burner insert individually, see SI83.70-P-0010A. For wiring harness malfunctions, see SI83.70-P0001B. Excessive quiescent current consumption of stationary heater (model series 211/219) Eliminate any excessive quiescent current consumption of the stationary heater in model series 211 by recoding the stationary heater control unit. FC 9074 (model series 215/220 AMG) The fuel signal (gasoline or diesel fuel) was absent on the CAN bus for more than 3 s — the fault is stored. If there is no complaint, the fault can be ignored and erased. Bus faults When bus faults are detected by Xentry Diagnostics (XD)/Xentry DAS, the system must be activated without sensors and the component causing the problem must be found by reconnecting the components individually. All fault codes must be erased before each new test.
Vehicle Climate Control - Troubleshooting-Function-Design-Operation - Current Passenger Car Models b
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2.1/25
Workshop
Stationary heater information in detail
Climate control diagnostic tree
General
The diagnostic trees provide a systematic and effective diagnostic aid for identifying the causes of complaints. In no way are these intended to replace the existing media, such as Xentry Diagnostics (XD)/ Xentry DAS, WIS and TIPS, but serve to link these together at important points and supplement them as necessary! In conjunction with the knowledge base, which contains important information on current common complaints concerning vehicle climate control systems, you are ideally equipped for your dayto-day work on Mercedes-Benz passenger car air conditioning systems and stationary heaters. Important notes/instructions on the diagnostic trees • The diagnostic trees only refer to the vehicle climate control or stationary heater systems. • The diagnostic trees help you to follow the correct procedures in the case of specific complaints. • When using the diagnostic trees always start on the first page otherwise you cannot be certain of diagnosing complaints properly and in a rapid, target-oriented manner. • After diagnosis and any necessary repairs, and before the vehicle is handed over, a function test is required in which the vehicle is again checked specifically for the complaint in question (observe the ambient conditions from the reception protocol!). • The fault trees are intended to provide assistance rather than binding work instructions.
EXPLANATION of the symbols used in the diagnostic trees:
Symbol Noise complaints Explanation Topic of customer complaint in the relevant chapter color Test steps, notes, causes, measures and further information
Ignition at stage 2, blower off
Noise present?
Yes
Branch at which you must make a decision with "Yes" or "No"
No
Continue with 6: Check "Ventilation/blower"
Reference to a further check
All models u83.00-P-0003A
Reference to a WIS document
Note:
Noises can be localized both acoustically and by sensing vibrations.
General information
2.2/1
b Vehicle Climate Control - Troubleshooting-Function-Design-Operation - Current Passenger Car Models
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Customer complaint
Stationary heater or air conditioning Note: Faults in other control units that have not been erased can prevent activation of the AAC/STH.
Perform initial quick test in DAS
Fault code(s) present? Check all control units Yes Print out fault code log
No
Process all fault codes present in all control units and then erase them
Climate control complaint: Perform AAC function check with DAS Stationary heater complaint: Perform STH function check with DAS
AAC/STH is OK? No
Yes
Yes
Fault code(s) present? Check all control units
No
Complaint eliminated?
Yes
No
Return vehicle to customer
Check coding with DAS. Air conditioning or stationary heater must be coded in CGW or EZS.
Note: Faults in other control units that have not been erased can prevent activation of the AAC/STH
AAC complaint? No
Yes
Continue with: 1. Complaint about climate control system
STH complaint?
Yes
Continue with: 2. STH system complaint
Vehicle Climate Control - Troubleshooting-Function-Design-Operation - Current Passenger Car Models b
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2.2/2
Climate control diagnostic tree
Basic check for vehicle climate control complaints
Climate control diagnostic tree
1. Complaint about climate control system
Perform flap alignment in DAS
Note: In the event of control or temperature problems, check both interior temperature sensors (if present)
Complaint eliminated?
Yes
Return vehicle to customer
No Note: Activate air conditioning (observe operating concept: A/C – ACOFF)
AAC noise complaint?
Yes
Continue with I: AAC noise complaint
No
AAC odor complaint?
Yes
Continue with II: AAC odor complaint
No
AAC function complaint?
Yes
Continue with III: Basic check for AAC function complaints
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b Vehicle Climate Control - Troubleshooting-Function-Design-Operation - Current Passenger Car Models
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Establish ambient conditions as per customer's description
Note: Equalization noises (whistling, howling) at the expansion valve even when the engine has been off for an extended period of time are physically unavoidable and can occur under certain temperature conditions. This is normal. Replacing parts does not remedy the problem!
Noise clearly coming from engine compartment?
Yes
Continue with
1
No Note: Noises can be localized both acoustically and by sensing vibrations. Observe safety information for work in the engine compartment with the engine running! When working on the blower, set ventilation to stage 0.
Noise from blower/air ducting?
Yes
No
Engine off, ignition on, deactivate blower Blower at stage 0 or press "0" button (depending on equipment installed)
No
Noise present?
Yes Ignition on, open all air outlets, manual air distribution at all levels, switch on front/rear blower in succession, start with lowest blower stage and run up to maximum blower output, temperature 26 °C/26 °C Note: • Noises e.g. due to the suction fan run-on, fans for interior temperature sensors and any additional fans for electronic components (e.g. radio, relays etc.) are normal. • Noises that occur after ignition switch-off are normal and may occur for some minutes after the engine is switched off due to changes in flap position (e.g. air recirculation flap).
Yes
Noise present?
No Ignition on, adjust settings as per customer description
Ascertain and rectify the cause of the fault
Yes
Noise can be localized?
No
Continued on the next page
Return vehicle to customer
2
Continue with function test 3: Blower/air ducting
Vehicle Climate Control - Troubleshooting-Function-Design-Operation - Current Passenger Car Models b
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Climate control diagnostic tree
I: AAC noise complaint
Climate control diagnostic tree
I: AAC noise complaint
Continued
2
Note: Both noises in the first few seconds, e.g. due to stepper motors or blower motors, and constant noises due to the heater circulation pump or the duovalves (also activated primarily in REST mode) are normal. Note the differences between air-regulated and water-regulated systems (see the components in the model descriptions and the explanation in the knowledge base).
Noise present?
Yes
No
No
Water-regulated system (see knowledge base)
Yes
DAS actuation • Shutoff valve • Heater circulation pump • Blend air flap(s)
DAS actuation • Duovalves • Heater circulation pump • Feed unit
Noise present? No Continue with function test 3: Blower/air ducting
Yes
Repair faults if necessary or explain operation of pulsed valves, shutoff valves and delivery pumps to customer (occurs primarily with REST function active)
No
Noise present?
Yes
Continue with
All model series: u83.00-P-0003A
1
Ascertain and rectify the cause of the fault
Return vehicle to customer
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b Vehicle Climate Control - Troubleshooting-Function-Design-Operation - Current Passenger Car Models
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Continued
1
Deactivate air conditioning + blower Blower at stage 0 or press "0" button (depending on equipment installed) Start the engine (Note: engine fan noise) Note: Use DAS to check that the refrigerant compressor is no longer actuated. In many model series, the refrigerant compressor does not switch off immediately after the button is pressed.
DGI83.55-P-045067
Listening test on belt drive Possible noise sources e.g.: Noise present? Yes - Tensioner/guide pulleys - Alternator - Power steering pump - Water pump - Suction fan bearing damage - Belt pulley bearing damage Refrigerant compressor
No Activate air conditioning. Temperature set to Io/Io, blower set to lowest stage
Ascertain and rectify the cause
Return vehicle to customer
Constant vibration, clattering or metallic noises? No
Yes
Check AC lines for contact with other components or the bodywork, and refasten if necessary. Noises are often caused by parts of the refrigeration circuit that are under stress.
Hissing noises?
Yes
Continue with function test 7: Refrigeration circuit evacuation
Note: A low fluid level in the air conditioning system and contamination of the line system with swarf or moisture may lead to noises in the line system or at the expansion valve.
No Note: Equalization noises (whistling, howling) at the expansion valve even when the engine has been off for an extended period of time are physically unavoidable and can occur under certain temperature conditions. This is normal. Replacing parts does not remedy the problem!
Other possible noises from the engine compartment (listening test): - Engine cooling circuit (water circuit) - Noise from vicinity of steering system/power steering pump - Resonance due to contact points - Noises from belt drive - Refrigerant compressor belt pulley damper rubbers (castanet-like rattling) - Refrigerant compressor belt pulley bearing damage
DGI83.55-P-045067
Continue with
3
Vehicle Climate Control - Troubleshooting-Function-Design-Operation - Current Passenger Car Models b
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2.2/6
Climate control diagnostic tree
I: AAC noise complaint
Climate control diagnostic tree
I: AAC noise complaint
Continued
3
Yes
Noise complaint eliminated? No DGI83.55-P-045067
Rpm-dependent howling noises from refrigerant compressor can be heard regardless of whether air conditioning activated or deactivated?
Yes
Check belt pulley of refrigerant compressor for bearing damage
No
Rpm-dependent suction noises can only be heard from refrigerant compressor with air conditioning activated?
Yes
Continue with function test 7: Refrigeration circuit evacuation
No
No DAS actuation • Shutoff valve • Heater circulation pump
Water-regulated system (see knowledge base)
Yes DAS actuation • Duovalves • Heater circulation pump • Feed unit
Noise present?
Yes
Repair faults if necessary or explain operation of pulsed valves, shutoff valves and delivery pumps to customer (occurs primarily with REST function active)
No Check for other possible noises due to leaks in the body while driving
Rectify fault
Return vehicle to customer
Note: Both noises in the first few seconds, e.g. due to stepper motors or blower motors, and constant noises due to the heater circulation pump or the duovalves (also activated primarily in REST mode) are normal. Note the differences between air-regulated and water-regulated systems (see the components in the model descriptions and the explanation in the knowledge base).
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Start with engine and ignition off
Smell test
Note: Moisture under the footwell carpet cannot usually be seen or felt by touch. Checking options: Lift carpet.
All models: f83.65-P-2370A
Eliminate moisture and its cause. Possibilities: Odor inside the closed vehicle? Yes Moisture detectable in floor mats or seat bolsters? Yes • • • • • • Body leaks Condensation hoses Check air intake Sliding roof drainage Firewall openings Water drains
No • • • • • • • • • •
No Check vehicle interior (e.g. trunk or under the seats) for foreign objects/contamination/vapors: Food leftovers Spilt fluids Fluids inside air outlets Cigarette smell/ashtrays Animal hair (pets) Pieces of clothing Air fresheners Interior (e.g. instrument panel, headliner, trim parts) Damping mats/fabrics (e.g. firewall, transmission tunnel. Smell test with shift gate opened) Miscellaneous
Note: The procedure is intended to ensure that the evaporator is completely dried out.
Warm up the vehicle in the workshop for at least 30 minutes and heat the interior (vehicle stationary) Air conditioning off (note control concept of A/C – ACOFF), blower at stage 2-3, maximum heating, recirculated air activated, outlets aimed at footwell, vehicle closed (doors, windows, sliding roof). No Odor due to foreign objects/ contamination?
Yes Inform customer Engine off, ignition on, open and actuate center air outlet, activate blower at stage 2-3, activate air recirculation. Temperature 22 °C
Note: Odors can also be produced by high strain on the engine, transmission/transmission tunnel or exhaust system. This can result in intensified odors in the interior.
Smell test
Odor inside the closed vehicle?
Yes
Remove filters, visual inspection and odor test in removed condition: • Interior filter (replace if necessary) • Combination filter (replace if necessary)
Yes Stronger with air recirculation?
No Continued on the next page
No Continued on the next page
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2
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Vehicle Climate Control - Troubleshooting-Function-Design-Operation - Current Passenger Car Models b
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Climate control diagnostic tree
II: AAC odor complaint
Climate control diagnostic tree
II: AAC odor complaint
Continued Continued
1
2
Note: The procedure is intended to ensure that the evaporator is completely wet and the odor can form.
Cause in ventilation system or engine compartment, visual inspection: • Duct between engine compartment and blower (clean if necessary) • Check air outlets for fluids that may have entered (is the odor limited to particular outlets?) and clean at the customer's expense if necessary • Check engine compartment for dirt, foreign objects, escaped fluids • If there is a constant or reproducible smell of exhaust gas, check the exhaust system
Start the engine, allow vehicle to cool for at least 30 minutes in the workshop (at standstill) Air conditioning on (note control concept of A/C – ACOFF), blower at stage 1-2, temperature Io/Io, windows open
Smell test Engine off, ignition on, air conditioning off, deactivate blower Blower at stage 0 or press "0" button (depending on equipment installed) Close vehicle (windows, doors, sliding roof) Note: Ignition must remain on for the entire duration. If necessary, ensure that charging voltage is maintained.
No
Odor eliminated?
Wait for 2 hours, the vehicle may not be started during this period. The blower must remain off for the entire duration.
Yes
Return vehicle to customer Engine off, ignition on, open and actuate center air outlet, activate blower at stage 2-3 Temperature 22 °C Note: In the first few minutes after an engine start, damp air may be blown out ("laundry smell"). This is due to natural causes. Repairs do not remedy the problem. All model series: Odor inside the closed vehicle? Yes • Eliminate odor • Check condensation hoses/drains and clean if necessary u83.30-P-0008A
Smell test
All model series: f83.65-P-2370A
No
Complaint not reproducible
f83.30-P-5556A Odor eliminated? No
f83.30-P-5555T Yes Return vehicle to customer
2.2/9
b Vehicle Climate Control - Troubleshooting-Function-Design-Operation - Current Passenger Car Models
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All fault codes in all control units read out and processed?
No
Continue with: Vehicle climate control complaints
Yes Check coding in DAS
Yes
Note: e.g. Coding OK? • PTC coding • Coding for hot countries
No Correct coding
Note for all model series: Complaints regarding the second seat row should be processed in the same way as complaints regarding the front seat row. Only process the separate fault tree if rear air conditioning (code 582) is installed. Yes
Complaint eliminated?
Return vehicle to customer
No
Complaint about fogged windows?
Yes
Continue with function test 1: Fogged windows
Complaints about temperature difference in passenger compartment • • • • • Top/bottom Right/left Front/rear Too cold/too warm Heater function
No Complaint about temperature difference in passenger compartment?
Continue with function test 2: Yes - Temperature differences passenger compartment — top/ bottom, right/left, front/rear - Too warm/too cold
No
Complaint about blower/air flow?
Yes
Continue with function test 3: Blower/air ducting
No Complaints, e.g.: • Flashing LEDs (except air recirculation button) • Total failure • Display errors • Button faults Complaint about AC operating unit? Yes Continue with function test 4: AC operating unit
No Complaints, e.g.: • No cooling • Insufficient cooling
Complaint about cooling of passenger compartment?
Yes
Continue with function test 5: Passenger compartment cooling
Vehicle Climate Control - Troubleshooting-Function-Design-Operation - Current Passenger Car Models b
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2.2/10
Climate control diagnostic tree
III: Basic check for AAC function complaints
Climate control diagnostic tree
Function test 1: fogged windows
Basic check for AAC function complaints
Continue with
Yes
1
Note: Windows can be more prone to fogging up with the air conditioning deactivated (refrigerant compressor may be automatically governed at low outside temperatures) or in air recirculation mode. Also see operating instructions.
Windows fogged on the outside? No Windows fogged on the inside
Note: Windows fog up on outside if defroster flap is leaky: fogged area starts at bottom and moves towards top
Check insides of windows for deposits/soiling and clean if necessary
Check customer settings (flaps, outlets, air conditioning activated?) and explain correct operation to the customer if necessary
Check air filter for moisture and replace or eliminate moisture if necessary
No
Moisture in the vehicle interior detectable? e.g. floor mats, door trim, floor panels Yes Eliminate moisture and its cause. Possibilities: • • • • • • Body leaks Condensation hoses Check air intake Sliding roof drainage Firewall openings Water drains Model series 169/245 f83.65-P-2370A
Complaint eliminated?
Yes
No Continue with function test 3: Blower/air ducting
Only with windows fogged on inside: Continue with function test 5: Passenger compartment cooling
No
Complaint eliminated?
Yes Return vehicle to customer
2.2/11
b Vehicle Climate Control - Troubleshooting-Function-Design-Operation - Current Passenger Car Models
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Continued
1
No
Windshield fogged on outside only in center
Yes
Note: Fogging of windows on the outside may occur due to an extreme temperature difference between the inside and the outside of the window combined with high air humidity. Adjust the blower outlets so that they are not aimed directly at the windows. Check customer settings and explain correct operation to the customer if necessary. Perform a function test of the defroster flap if necessary.
Note: Windows fog up on outside if defroster flap is leaky: fogged area starts at bottom and moves towards top
Manual diffuser outlet: This outlet is only controlled manually on some model series and not by the air conditioning control system (see model series description). Check customer settings and explain correct operation to the customer if necessary. Perform a function test of the diffuser outlet if necessary.
Return vehicle to customer
Vehicle Climate Control - Troubleshooting-Function-Design-Operation - Current Passenger Car Models b
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2.2/12
Climate control diagnostic tree
Function test 1: fogged windows
Climate control diagnostic tree
Function test 2a (code 580 and 581): Temperatures differences in passenger compartment top/bottom, left/right, front/rear
Note: If installed, pay attention to cold air reduction feature (see knowledge base). Basic check for AAC function complaints
Complaint about rear air conditioning system (SA code 582)? No
Yes
Continue with function test 2b: Rear air conditioning Model series 211 b83.40-P-3001A
Yes DAS actuation • • • • Duovalves Heater circulation pump Feed unit Engine-side shutoff valves
Water-regulated system? (See knowledge base)
No DAS actuation • • • • Shutoff valve/motor Blend air flap(s) Heater circulation pump Engine-side shutoff valves
No
Check OK? Yes DAS actuation Center air outlet flap Note on outside temperature sensor (B14): When outside temperatures are increasing, the lower sensor value is retained and stored. It is only readjusted when the vehicle speed is > 40 km/h. For this reason, a plausibility check of this sensor is not meaningful.
No
Check OK? Yes If installed, check the following sensors for plausibility using DAS • In-car temperature sensor (B10/4) • Overhead control panel in-car temperature sensor (N70b1) • Sun sensor (B32/3) • Pressure sensor (B12 or B12/2) • Outlet air temperature sensor • Heat exchanger sensor • Evaporator sensor
Note: Check whether one or two interior temperature sensors are installed (see knowledge base).
No
Check OK? Yes
Note on AUTO mode: Cooling: The center level is intentionally actuated more powerfully than the other levels when cooling. Heating: The warm air output is intentionally more powerful at the foot level during heating. The center level may be closed in AUTO mode (including in rear). Booster blowers may be shut off in AUTO mode.
No
Is the evaporator sensor properly seated in the AC housing? Yes
Continue with
Continue with
1
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2
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b Vehicle Climate Control - Troubleshooting-Function-Design-Operation - Current Passenger Car Models
Continued
Continued
1
Ascertain and rectify the cause of the fault
2
Yes
Complaint eliminated? No Continue with function test 3: Blower/air ducting
Yes
Complaint eliminated? No Check internal sealing of body for leakage/drafts and eliminate if necessary
Model series 203/209 DGI72.00-P-036450
Normalize power windows and sliding roof
AAC operation is OK? Yes
No
Continue with function test 5: Passenger compartment cooling
Return vehicle to customer
Vehicle Climate Control - Troubleshooting-Function-Design-Operation - Current Passenger Car Models b
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2.2/14
Climate control diagnostic tree
Function test 2b: rear air conditioning (SA 582): Temperatures differences in passenger compartment top/bottom, left/right, front/rear
Climate control diagnostic tree
Function test 3: blower/air ducting
Basic check for AAC function complaints
1. Check interior combination filter for contamination and replace if necessary 2. Noise check of interior blower fan for unobstructed movement/foreign objects; remove foreign objects if necessary 3. Visual check of duct between engine compartment and blower, clean if necessary
Yes
Complaint eliminated?
No Use DAS to check blower regulator and motor individually: Model series 163 DGI83.30-P-007993 1. Check power supply to component A32 and N22/7 2. Check component A32n1 via actual value 3. Test actuation of component A32m1. 4. Check signal to component A32
Blower running. No air from any outlets?
Yes
The evaporator may be iced up.
No Yes Continue with function test 5: Complaint eliminated? Passenger compartment cooling
No Check air recirculation flap and, if applicable, back pressure valve (see model series documentation) for proper operation • Opens correctly/closes correctly/leaktight/complete • Opens/closes in correct direction Note on AUTO mode: Yes Complaint eliminated? Cooling: The center level is intentionally actuated more powerfully than the other levels when cooling. Heating: The warm air output is intentionally more powerful at the foot level during heating. The center level may be closed in AUTO mode (including in rear). Booster blowers may be shut off in AUTO mode.
No
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Continued on the next page
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2
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Continued
Continued
1
2
Test booster blower via DAS actuation
Yes
Complaint eliminated?
No Note: Continue with function test 8: Manual flap test For function test 8: Do not test flaps in AUTO mode, actuate them individually.
No
Function OK?
Yes
Ascertain and rectify the cause
Complaint eliminated?
No
Back to starting point (e.g. Check I, II, 1 or 2)
Yes
Return vehicle to customer
Vehicle Climate Control - Troubleshooting-Function-Design-Operation - Current Passenger Car Models b
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2.2/16
Climate control diagnostic tree
Function test 3: blower/air ducting
Climate control diagnostic tree
Function test 4: AC control panel
Note:The operating unit is NOT usually the cause of problems with the air conditioning. First check all the other components in the air conditioning systems in accordance with the diagnostic trees! Note: On most model series, the air recirculation button flashes in diagnostic mode. This is not a fault; it indicates diagnostic mode when the DAS is plugged in.
Note: Rear operating units on vehicles with code 581 are really only switches (except on model series 220) that transfer signals to the front air conditioning control unit.
Basic check for AAC function complaints
Depending on model series: ACOFF lights up constantly or A/C flashes after actuation and goes out again? Yes f83.30-P-1760AK f83.30-P-1760CW f83.30-P-1760RT f83.30-P-1760V f83.30-P-1782A
No
No
Operating unit nonfunctional? Yes Ensure proper power supply
Note: Depending on the vehicle in question, the coding indicating whether or not an air conditioning system is installed is coded in different control units (e.g. EZS, CGW etc.).
Code air conditioning (variant coding)
Individual buttons nonfunctional? Yes
No Reset: Complaint eliminated? No • • • • Ignition off, remove key Unplug DAS Perform circuit 30 reset (5 minutes) Normalize flaps, windows, sliding roof
Yes
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Return vehicle to customer
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Continued
1
Perform button test using DAS
Process any faults found
Reset: Complaint eliminated? No • • • • Ignition off, remove key Unplug DAS Perform circuit 30 reset (5 minutes) Normalize flaps, windows, sliding roof
Yes
Return vehicle to customer
Continued
2
No
Display complaint?
Yes
No
Does the complaint occur intermittently?
Yes
Perform lights test in DAS
Check function of day/night sensor
Check connector at operating unit and at driver-side SAM
Reset: • • • • Ignition off, remove key Unplug DAS Perform circuit 30 reset (5 minutes) Normalize flaps, windows, sliding roof No Complaint eliminated?
Yes
Return vehicle to customer
Vehicle Climate Control - Troubleshooting-Function-Design-Operation - Current Passenger Car Models b
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2.2/18
Climate control diagnostic tree
Function test 4: AC control panel
Climate control diagnostic tree
Function test 5: passenger compartment cooling
Basic check for AAC function complaints
M273 in model series 221 DGI83.55-P-036469
Model series 169 DGI83.30-P-038563
Note: The test can be found under DAS menu item "Function check".
Perform DAS "Refrigerant circuit test"
Note: This test may also help rectify problems with rear systems (SA 582). Then continue with test 2b for rear systems (SA 582).
After end of DAS test, perform manual test of air conditioning without DAS. Pay attention to complaints: Adjust settings and ambient conditions as per reception protocol.
Yes
Complaint eliminated?
No
Continue with function test 2: • Temperature differences in passenger compartment top/bottom, right/left, front/rear • Too cold/too warm Yes Function test 7: Evacuation of refrigeration circuit already performed?
No
Return vehicle to customer
Continue with function test 7: Refrigeration circuit evacuation
2.2/19
b Vehicle Climate Control - Troubleshooting-Function-Design-Operation - Current Passenger Car Models
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Note: After opening the refrigeration circuit, new sealing rings must always be used at the separation points when assembling. Care must be taken to ensure that they are not pinched when assembling the parts (assemble the lines straight).
Note: Temperature changes during the pressure test can cause pressure surges. It is essential to ensure constant ambient conditions.
Basic check for AAC function complaints
Continue with function test 6b: Vehicle outside term of warranty? Complaint about refrigeration circuit leaks on vehicles outside term of warranty
All model series: c83.30-P-0005-01A
Evacuate system. Then fill system with nitrogen and maintain pressure at 15 bar
Apply leak detector spray to all relevant parts
Leak found?
Yes
No
All model series: DGI83.00-P-037689
Release nitrogen, fill system with specified quantity of refrigerant, return the oil quantity removed to the system and add contrast agent Note: This operation step is intended to ensure that there are no residual traces present from repairs performed in the past. Leaks can only be clearly localized once any traces of old contrast agent are removed.
Before leak detection: • Illuminate the entire engine compartment with a UV lamp • Remove any traces of contrast agent using special cleaner • Engine wash
Leak detection with the aid of contrast agent and UV lamp
Yes Leak found? No Remove E-valve and inspect area between E-valve and firewall for contrast agent with UV
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Continued on the next page
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2
2.2/20
Vehicle Climate Control - Troubleshooting-Function-Design-Operation - Current Passenger Car Models b
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Climate control diagnostic tree
Function test 6: refrigeration circuit leaks
Climate control diagnostic tree
Function test 6: refrigeration circuit leaks
Continued Continued
1
2
Leak found?
Yes
No
All model series: u83.30-P-0001A
Check evaporator for leaks separately at 20 bar
All model series: c83.30-P-0005-01A
Replace evaporator
No
Evaporator leaktight?
Yes Use new seals when assembling
• • • • •
Replace any leaking components Use new seals Illuminate the entire engine compartment with a UV lamp Remove traces of contrast agent using special cleaner Engine wash
Fill system with specified quantity of refrigerant and return the oil quantity removed to the system.
Note: After refilling, if ACOFF is permanently lit or if A/C flashes after actuation and then goes out again, perform a reset: • Ignition off, remove key • Unplug DAS • Perform circuit 30 reset (5 minutes) • Normalize flaps, windows, sliding roof
Yes
Complaint eliminated?
No
Continue with function test 5: Return vehicle to customer Passenger compartment cooling
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Basic check for AAC function complaints
Yes
Ask customer: Was vehicle already in workshop with this complaint?
No Check vehicle age and maintenance after expiry of warranty period
Note: Yes Ask customer: Did the complaint occur suddenly or in the recent past? "Recent past" means, for example, that the air conditioning still operated properly after the last winter period.
No Evacuate system and establish the fill quantity
Yes
System significantly underfilled (fill quantity < 50%)?
No Refill system with specified quantity of refrigerant, return the oil quantity removed to the system and add contrast agent
• Illuminate the entire engine compartment with a UV lamp • Remove any traces of contrast agent using special cleaner • Engine wash
Note: This operation step is intended to ensure that there are no residual traces present from repairs performed in the past. Leaks can only be clearly localized once any traces of old contrast agent are removed.
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2.2/22
Climate control diagnostic tree
Function test 6b: refrigeration circuit leaks Complaint about vehicle outside term of warranty
Climate control diagnostic tree
Function test 6b: refrigeration circuit leaks Complaint about vehicle outside term of warranty
Continued
1
Continued
2
Note: If AC/ACOFF flashes continuously after complete refill, perform reset. Reset: Function test • Ignition off, remove key • Unplug DAS • Perform circuit 30 reset (5 minutes) • Normalize flaps, windows, sliding roof
Discuss further procedure, repair and consequential costs with customer. It may be possible to proceed as per the diagnostic trees in the Technology Guide for Vehicle Climate Control regardless of the age of the vehicle.
Discuss with customer: Vehicle check: • For leaktightness after 3 months using UV leak detection • Or after repeat occurrence of complaint
Continue with function test 6: Refrigeration circuit leakage
Return vehicle to customer
2.2/23
b Vehicle Climate Control - Troubleshooting-Function-Design-Operation - Current Passenger Car Models
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Basic check for AAC function complaints
Yes
Does the shaft of the refrigerant compressor turn when the engine is running?
No
• Extract and weigh refrigerant • Weigh extracted oil
• Extract and weigh refrigerant • Weigh extracted oil
Fill quantity < 80% of standardized filling quantity?
No
Refrigeration circuit overfilled?
No
Yes
Yes
Result of DAS refrigeration circuit test "The refrigeration circuit is overfilled or clogged"?
Yes
All model series: c83.30-P-1782-01A
No
Continue with Check 6: Refrigeration circuit leakage
Fill system with specified quantity of refrigerant and return the oil quantity removed to the system.
Note: After refilling, if ACOFF is permanently lit or if A/C flashes after actuation and then goes out again, perform a reset: • Ignition off, remove key • Unplug DAS • Perform circuit 30 reset (5 minutes) • Normalize flaps, windows, sliding roof
Yes
Complaint eliminated?
No
Continue with function test 5: Return vehicle to customer Passenger compartment cooling
Vehicle Climate Control - Troubleshooting-Function-Design-Operation - Current Passenger Car Models b
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2.2/24
Climate control diagnostic tree
Function test 7: refrigeration circuit evacuation
Climate control diagnostic tree
Function test 8: manual flap test
Note: Model series 169 with code 580: Certain flaps are controlled manually using Bowden cables. Note: This test should be performed without DAS. It serves to identify broken actuating arms or defects in kinematically linked flaps which cannot be detected electrically.
Start engine
Note: The FlashFog logic prevents actuation of the outlets for the windshield for approx. 30 seconds.
Activate air conditioning (observe operating concept: A/C – ACOFF) Blower stage 2-3., temperature 18 °C (but not LO/LO)
Note: Do not check the flaps in AUTO mode, but actuate them individually.
Note: If installed, pay attention to cold air reduction feature (see model series documentation on
Manually check individual flaps: Is sufficient air noticeable at all flaps? Manually set the following flap positions in sequence and check: • Center air outlet (1) (note cold air reduction and center outlet kinematics depending on equipment installed, see model description) • Side air outlets in dashboard (2) • Footwell air outlets (3) • Windshield (4) • Diffuser outlet (5) • Rear compartment - Center vent (6a) - Side vents (6b) - Footwell vents (6c)
Repair faults if necessary, return to starting point if necessary
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b Vehicle Climate Control - Troubleshooting-Function-Design-Operation - Current Passenger Car Models
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Note: This diagnostic tree only applies to the STH system. See "Climate control diagnostic tree" for function "Heating during driving operation".
Check tank content: Tank must be at least ¼ full with vehicle parked on level ground.
Note on transitional period between seasons: Is the fuel in the tank suitable for winter conditions? The STH fuel line may be jellified.
Run stationary heater to clean it out: Start STH using DAS, open all windows, set temperature control to "High" Note: Air bubbles may form in the fuel line if the STH is not used for an extended period or due to the effect of heat on the fuel line. Refill fuel line by restarting the STH several times. In particular, this may be necessary the first time the STH is operated after the summer period.
Note: Event "Consumer shutoff" in the vehicle power supply control unit (if installed) causes the STH to remain deactivated or to shut off if there is undervoltage in the on-board electrical system. If consumer shutoff is active or stored in the vehicle power supply control unit, the on-board electrical system, power supply and/or vehicle battery(-ies) must be checked.
Note: If the STH is electronically locked (fault interlock), it cannot be activated. Deactivate the (crash) lock using DAS if necessary.
Complaint eliminated?
Yes
Return vehicle to customer
No
STH noise complaint?
Yes
Continue with I: STH noise complaint
No
STH function complaint?
Yes
Continue with II: Basic check for STH function complaints
Vehicle Climate Control - Troubleshooting-Function-Design-Operation - Current Passenger Car Models b
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2.3/1
Stationary heater diagnostic tree
2. Complaint about stationary heater system
Stationary heater diagnostic tree
I: STH noise complaint
Reproduce ambient conditions as per customer description (see reception protocol) Note: The engine is generally cold when the customer uses the STH, allow vehicle to cool overnight if necessary.
Check: Note: Model series 203 up to year of manufacture 2004: Check air intake hose of STH for protruding damping material and replace if necessary. Check: 1 Air intake hose for STH for unrestricted flow • Clogging • Attachment/clear intake opening 2 STH installation space for foreign objects • Exhaust pipe for damage or clogging. Test exhaust pipe air outlet using DAS "Combustion air blower actuation". • Output and rotation direction of STH combustion air blower motor (if motor connector was disconnected, e.g. during repair, and then reconnected with the polarity reversed, the motor may be rotating in the wrong direction). Check rotation direction via exhaust pipe air outlet using DAS "Combustion air blower actuation".
Complaint eliminated?
Yes
Return vehicle to customer
No Start STH using switch on control panel Pay attention to activation/shutoff conditions of STH (including ambient conditions such as outside temperature and coolant)
Intake/ combustion noises? No
Yes
A certain level of noise due to combustion and air intake is unavoidable, particularly when the STH is started, and is considered normal. If necessary, check the CO2 setting using DAS.
If necessary, check/adjust exhaust emission values of STH Note: The noises produced by the STH can change according to its operating condition (e.g. startup, combustion, run-on). This is normal.
f83.70-P-1177M
Ensure STH is operating properly.
Inform customer of facts.
Continued on the next page
Return vehicle to customer
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Continued
Noise is normal: Following causes are known: Deflagration noises? Yes • Insufficient tank fill level, vehicle is often positioned on an excessively steep slope • Outgassing (gasoline engines), fuel in feed line evaporates over time Remedy: Use STH more often
No
Inform customer of facts.
Return vehicle to customer
Noise is normal: Continuous combustion air blower noise? Yes • Can change as rpm of combustion air blower changes (e.g. during startup) • Frequency may be uniform (under full load)
No Inform customer of facts.
Return vehicle to customer
Noise is normal: Clicking noises? Yes • Pulsing noise of fuel metering pump • Pulsing noise of pulsed valves or feed unit
Check metering pump for correct seating, check soundproofing (pump may not contact body).
No Return vehicle to customer
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Vehicle Climate Control - Troubleshooting-Function-Design-Operation - Current Passenger Car Models b
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2.3/3
Stationary heater diagnostic tree
I: STH noise complaint
Stationary heater diagnostic tree
I: STH noise complaint
Continued
Gurgling noises from engine cooling system?
Yes
Check check valve in engine vent line (model series 171, model series 211 with M271)
No Possible air pocket in engine water circuit. Remedy: Refill engine cooling system using vacuum (it may be necessary to perform this procedure several times) Air pockets can also be caused by repair work on the cooling system.
Noise source not in heating system
Yes
Noise still exists?
No
Localize noise source and eliminate, inform customer
Return vehicle to customer
2.3/4
b Vehicle Climate Control - Troubleshooting-Function-Design-Operation - Current Passenger Car Models
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Complaint: stationary heater smokes?
Yes
Continue with function test 1: Stationary heater smokes
No
Continue with function test 2: Activation not possible using remote control, control panel switch or instrument cluster (start time preselection)? Yes Activation not possible using remote control, control panel switch or instrument cluster (start time preselection) stationary heater does not start
No
Activation using remote control faulty?
Yes
Continue with function test 3: Activation using remote control faulty
No
Activation using switch on control panel faulty?
Yes
Continue with function test 4: Activation using switch on control panel faulty
No
Activation on instrument cluster (start time preselection) faulty?
Yes
Continue with function test 5: Activation on instrument cluster (start time preselection) faulty
No
Complaint: Poor STH heat output?
Yes
Continue with function test 6: Poor STH heat output
Vehicle Climate Control - Troubleshooting-Function-Design-Operation - Current Passenger Car Models b
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Stationary heater diagnostic tree
II: Basic check for STH function complaints
Stationary heater diagnostic tree
Function test 1: stationary heater smokes
Basic check for STH function complaints
Check: • Exhaust pipe for damage or clogging. Test exhaust pipe air outlet using DAS "Combustion air blower actuation". • Output and rotation direction of STH combustion air blower motor (if motor connector was disconnected, e.g. during repair, and then reconnected with the polarity reversed, the motor may be rotating in the wrong direction). Check rotation direction via exhaust pipe air outlet using DAS "Combustion air blower actuation".
Note: Model series 203 up to year of manufacture 2004: Check air intake hose of STH for protruding damping material and replace if necessary.
Check: 1 Air intake hose for STH for unrestricted flow • Clogging • Attachment/clear intake opening 2 STH installation space for foreign objects
Ensure air supply for STH present
No
Air supply for STH present?
Yes Ensure stationary heater is operating properly Run stationary heater to clean it out: Start STH using DAS, open all windows, set temperature control to "High" Note: Air bubbles may form in the fuel line if the STH is not used for an extended period or due to the effect of heat on the fuel line. This can result in smoke formation. Refill fuel line by restarting the STH several times. In particular, this may be necessary the first time the STH is operated after the summer period.
Return vehicle to customer
Yes
STH runs without smoking?
No Note AR83.70-P-1177M: Readjust exhaust emission values of STH Check/adjust exhaust emission values of STH Adjust exhaust emission values using Star Diagnosis: Menu item Control units-Stationary heaterControl unit adaptations-CO2 setting
STH runs without smoking?
No
Yes Ensure that remote control, switch on control panel and combined function of stationary heater are operating properly Continue with function test 2: Activation not possible using remote control, control panel switch or instrument cluster (start time preselection) stationary heater does not start
Return vehicle to customer
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Activation of STH not possible using remote control, control panel switch or instrument cluster stationary heater does not start
Note: The battery cannot reach its optimum charge level if the vehicle is driven over short distances at a low engine speed with high current consumers frequently switched on (e.g. heated rear window, heated seats etc.). General rule for optimum charge level: heating time = driving time
Basic check for STH function complaints
Check on-board power supply voltage/ vehicle battery(-ies)
Check STH shutoff voltage, adjust if necessary
Note: Event "Consumer shutoff" in the vehicle power supply control unit (if installed) causes the STH to remain deactivated or to shut off if there is undervoltage in the onboard electrical system. If consumer shutoff is active or stored in the vehicle power supply control unit, the on-board electrical system, power supply and/or vehicle battery(-ies) must be checked.
No
Voltage under switch-off threshold? (see DAS for values)
Yes
Test and charge battery(-ies) Check fuel quantity in fuel tank Ensure stationary heater is operating properly Fuel tank must be at least ¼ full with vehicle parked on level ground Return vehicle to customer
No
Sufficient fuel in tank?
Yes
Note: Air bubbles may form in the fuel line if the STH is not used for an extended period or due to the effect of heat on the fuel line. Refill fuel line by restarting the STH several times. In particular, this may be necessary the first time the STH is operated after the summer period.
Fill up with fuel
Complaint eliminated? Yes
No
Refill fuel line by starting STH several times, pay attention to fault interlock.
Note: Fault interlock can be erased using DAS.
Continue on the next page with
Continue on the next page with
1
2
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Stationary heater diagnostic tree
Function test 2:
Stationary heater diagnostic tree
Function test 2:
Activation of STH not possible using remote control, control panel switch or instrument cluster stationary heater does not start
Continued
Continued
1
Yes
2
Complaint eliminated? No Check intake hose for STH in fuel tank/extend if necessary, check for correct position Model series 203, 209, 211, 219: v83.70-P-0010A
Note: Advise the customer that air bubbles can form in the fuel line if the STH is not used for a long time or due to the effects of high temperature. Refill fuel line by restarting the STH several times.
Inform customer "Fuel tank muss must be at least ¼ full"
Run stationary heater to clean it out: Start STH using DAS, open all windows, set temperature control to "High"
Yes
Complaint eliminated?
Return vehicle to customer
No
Electrical connector on heater unit is OK?
u83.70-P-0001B
Repair: repair wiring harness for power supply
Yes
Continued on the next page
2.3/8
b Vehicle Climate Control - Troubleshooting-Function-Design-Operation - Current Passenger Car Models
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Activation of STH not possible using remote control, control panel switch or instrument cluster stationary heater does not start
Continued
Check fuel delivery quantity of STH metering pump with DAS
Fuel quantity is OK?
Yes
Ensure fuel supply is OK. Affected components: • Pump • Lines If necessary, use separate fuel supply, check line components individually for clogging
Yes
STH is OK?
No
Check • Circulation pump • Stationary heater shutoff valve Replace if necessary Note: See component overview for installation location
Yes
STH is OK?
No
All model series u83.70-P-0010A
Yes
Burner inserts replaceable separately?
No
Replace glow pin with burner insert
Replace STH and teach in again
Ensure that remote control, switch on control panel and combined function of stationary heater are operating properly
Return vehicle to customer
Vehicle Climate Control - Troubleshooting-Function-Design-Operation - Current Passenger Car Models b
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2.3/9
Stationary heater diagnostic tree
Function test 2:
Stationary heater diagnostic tree
Function test 3: remote control activation faulty
Note: The range and/or operation of the remote control can be influenced or impaired by a number of different factors (e.g. garage door openers, cordless telephones, transmitter masts, power lines) or obstacles (e.g. buildings). Inform customer if necessary. Basic check for STH function complaints
Check batteries of remote control
Press "ON" button, LED must light up green Press "OFF" button, LED must light up red
T70 and T90: Does the LED in the remote control transmitter flash orange? No T100: Does a battery symbol appear in the display of the remote control?
Yes
No
Yes Replace batteries
Complaint eliminated?
Yes
Return vehicle to customer
No Check plugs/connections/lines/power supply of Telestart
Check whether antenna connection/telephone connection are connected correctly or swapped incorrectly
Complaint eliminated?
Yes
Return vehicle to customer
No
Continue with
1
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Note, T70 only: STH cannot be actuated in warm outside temperatures (ventilation is performed instead). In this case, switch the ignition to stage 2 (circuit 15 on) and set the temperature range on the AC operating unit to Max/Hi. The STH now outputs warm air despite the high outside temperature.
Continued
1
Teach in STH remote control manually: T70/90/100: • In the vehicle, hold down the instant heat button on the control panel until the red LED in the instant heat button starts to flash. • Release button • Within 5 sec, press the OFF button on the remote control until the red LED on the remote control flashes • Teach-in process complete Note, T70 only: Remote control T70 may not be inside the vehicle during the teach-in process.
Teach-in process successful? No Teach in remote control again using DAS:
Yes
Menu item Stationary heater, Control unit adaptations, Teach-in of component A8/3
Teach-in process successful? No
Yes
Check receiver of radio remote control using second remote control (teach in if necessary)
Yes
Receiver of radio remote control is OK? No
Check wiring harness and STH antenna splitter connectors
Replace defective radio remote control
Receiver of radio remote control is OK? No Replace radio remote control receiver
Yes
Ensure that remote control, switch on control panel and combined function of stationary heater are operating properly
Return vehicle to customer
Vehicle Climate Control - Troubleshooting-Function-Design-Operation - Current Passenger Car Models b
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2.3/11
Stationary heater diagnostic tree
Function test 3: remote control activation faulty
Stationary heater diagnostic tree
Function test 4: Activation using switch on control panel faulty
Basic check for STH function complaints
Perform switch test using DAS
Check wiring
Yes
Switch OK according to DAS? No
Ensure switch operates properly, replace if necessary
Ensure that remote control, switch on control panel and combined function of stationary heater are operating properly
Return vehicle to customer
2.3/12
b Vehicle Climate Control - Troubleshooting-Function-Design-Operation - Current Passenger Car Models
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Basic check for STH function complaints Note: Check coding, STH must be coded in CGW or EZS. Set clock No Time set correctly? Yes
Note: Inform customer No Start/departure time selected correctly? Yes Logic change on new model series: entry of departure time instead of heater start time
Wiring of instrument cluster is OK? No
Yes
Replace wiring
See: Stationary heater system overview
Check bus subscribers individually and ensure that they operate properly
Ensure that remote control, switch on control panel and combined function of stationary heater are operating properly
Return vehicle to customer
Vehicle Climate Control - Troubleshooting-Function-Design-Operation - Current Passenger Car Models b
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2.3/13
Stationary heater diagnostic tree
Function test 5: Activation on instrument cluster faulty
Stationary heater diagnostic tree
Function test 6: Poor heat output
Basic check for STH function complaints
Continue with 1: Complaint about climate control system
Yes
Does complaint also occur during driving operation?
No Note: If the on-board power supply voltage drops under the critical value during STH operation, the STH switches off and cannot regulate to the desired temperature. Note: An insufficient heating period or excessively low preselected temperature on the control panel can result in the interior compartment not being preheated to the desired temperature.
Set clock
No
Time set correctly? Yes
Note: Inform customer No Start/departure time selected correctly? Yes Logic change on new model series: entry of departure time instead of heater start time
Temperature preselection set correctly on instrument cluster?
Yes
Note: On model series 211, 251 and 164, the specified temperature for the stationary heater can be preselected in the range from 20 to 24 °C. At temperatures lower than 20 °C, the temperature is automatically regulated to 20 °C and at temperatures greater than 24 °C, the temperature is automatically regulated to 24 °C.
No Continue with function test 2: Inform customer about function: STH heats up to the temperature set on the AC operating unit Activation not possible using remote control, control panel switch or instrument cluster (start time preselection) stationary heater does not start
Return vehicle to customer
2.3/14
b Vehicle Climate Control - Troubleshooting-Function-Design-Operation - Current Passenger Car Models
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The knowledge base contains important information and describes general features of the vehicle climate control systems on Mercedes-Benz passenger cars. The indexes for the individual model series describe the features specific to each model. These are structured as follows: • Overview of operation and a description of the individual functions • Data flow chart • Block diagram • Overview of the relevant components (actuators and sensors) with installation location*, function, task and, where relevant, the consequences of failure *The installation locations are always specified in the direction of travel. These may differ in right-hand drive vehicles, where the components are generally to be found on the opposite side of the vehicle.
Remedies for retrofitted stationary heaters This guide only deals with stationary heaters that are installed in the vehicle at the plant (identifiable via SA code 228). The advice contained in this guide may help to troubleshoot retrofitted systems but has only been tested on systems installed ex plant. For questions regarding complaints about retrofitted variants, contact your relevant LC or the manufacturer Webasto at the hotline number +49 (0)1805-932278.
i Note The system overview, data flow and block diagrams are shown on a vehicle with the full equipment (with codes 581, 582). The differences in the components in the various equipment packages (code 580, 581, 582) are shown in the overview of components.
i Note The production breakpoints listed are approximate. They may vary as modifications are phased in to production.
Vehicle Climate Control - Troubleshooting-Function-Design-Operation - Current Passenger Car Models b
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Knowledge base
General
Knowledge base
General
Code list: Code
228 413 414 417 450 511 512 527 580 581 582 584 589 848 872 873 875 913 965
Designation
Stationary heater Panoramic sunroof Power glass tilting/sliding roof Louvered sunroof Taxi version Audio 50 APS including DVD changer COMAND APS including DVD changer COMAND APS (with navigation) Automatic air conditioning Comfort automatic air conditioning Rear air conditioner Rear power windows (2 doors) Booster blower for rear-seat passengers Power side vent windows Electrically heated left and right rear seats Right and left front seat heaters Heated windshield washer system Air conditioning preinstallation for hot countries Electrical preinstallation/rental vehicle
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b Vehicle Climate Control - Troubleshooting-Function-Design-Operation - Current Passenger Car Models
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Water-regulated air conditioning Model 171, 215/220 and rear air conditioning in model 221
The outlet air temperature of the air conditioning system is controlled via the temperature of the heater heat exchanger (4) and the evaporator (3). Pulsed valves (5) control the flow of coolant through the heater heat exchanger (4). Pulsed valves (5) can only be either fully open or fully closed; intermediate positions are not possible. The closing and opening times of the pulsed valve (5) depend on the target temperature that has been selected in the vehicle interior. Evaporator and heat exchanger sensors are used for regulation.
Cooling When the temperature selector wheel is at the "Min" position or there is no heating request from the AAC [KLA] control unit, the pulsed valve (5) is closed and the supply to the heater heat exchanger (4) is shut off. The fresh or recirculated air is directed to the air outlets without being heated by the heater heat exchanger (4).
P83.30-4422-00 For legend see 3.2/3
Temperature control When the temperature selector wheel is in an intermediate position, the pulsed valve (5) is opened according to the heat requirement in the interior compartment. The lower the heat requirement, the shorter the opening times of the pulsed valve (5). Therefore, less warm coolant flows through the heater heat exchanger (4) and the heat output is reduced.
P83.30-4423-00 For legend see 3.2/3
Vehicle Climate Control - Troubleshooting-Function-Design-Operation - Current Passenger Car Models b
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Knowledge base
Water and air-regulated air conditioning systems
Knowledge base
Water and air-regulated air conditioning systems
Heating When the temperature selector wheel is at the "Max" position or there is a maximum heating request from the AAC [KLA] control unit, the pulsed valve (5) is opened and the supply to the heater heat exchanger (4) is constantly open. The fresh or recirculated air is heated at the warm heater heat exchanger (4) and directed to the air outlets.
P83.30-4424-00 For legend see 3.2/3
Air-regulated air conditioning Model 164, 169、245, 203, 209, 211, 219, 221 Front air conditioning, 230, 251, 204, X164, 207, 212
The outlet air temperature of the air conditioning is regulated via blend air flaps. These steplessly regulate the air flow of warm air which flows through the heater heat exchanger (4) and fresh air which flows through the evaporator (3). The evaporator sensor and, depending on model, other temperature sensors in the air outlets (cockpit) air used to regulate the air flow.
Cooling When the temperature selector wheel is at the "Min" position or there is no heating request from the AAC [KLA] control unit, the fresh or recirculated air is directed by the blend air flap through the evaporator (3) and past the heater heat exchanger (4). The fresh or recirculated air reaches the air outlets without being heated.
P83.30-4419-00 For legend see 3.2/3
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Temperature control When the temperature selector wheel is in an intermediate position, the blend air flap is regulated according to the heat requirement in the interior compartment. As the heat requirement increases, more fresh or recirculated air is directed from the evaporator (3) via the heater heat exchanger (4). The temperature of the air mixture rises and is directed to the air outlets.
P83.30-4420-00
Heating When the temperature selector wheel is at the "Max" position or there is a maximum heating request from the AAC [KLA] control unit, the fresh or recirculated air drawn in by the blower motor is directed by the blend air flap through the warm heater heat exchanger (4) only where it is heated. The heated air is directed to the air outlets.
P83.30-4421-00
Legend 1 2 3 4 5 Dust filter Activated charcoal filter Evaporator Heater heat exchanger Pulsed valve
Vehicle Climate Control - Troubleshooting-Function-Design-Operation - Current Passenger Car Models b
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Knowledge base
Water and air-regulated air conditioning systems
Knowledge base
Refrigerant circuit
Without rear air conditioning
Legend, see page 3.2/5
P83.40-3773-00
With rear air conditioning
Legend, see page 3.2/5
P83.40-3774-00
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Hybrid with rear air conditioning
P83.40-4565-00
A B C D 1 2 3 4
High pressure, gaseous High pressure, liquid Suction pressure, liquid Suction pressure, gaseous Refrigerant compressor Condenser Fluid reservoir Refrigerant pressure and temperature sensor
5 6 7 8 9 10 11 12
Expansion valve Front evaporator Front evaporator temperature sensor Shutoff valve Rear evaporator Rear evaporator temperature sensor High-voltage battery module High-voltage battery cooling shutoff valve
Vehicle Climate Control - Troubleshooting-Function-Design-Operation - Current Passenger Car Models b
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Knowledge base
Refrigerant circuit
Knowledge base
Heating circuit
Standard equipment
4
3
2
1
9
Legend, see page 3.2/7
P83.25-2292-00
With stationary heater and heated windshield washer system
4
3 5 2
6
3
1
9
Legend, see page 3.2/7
P83.25-2294-00
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With stationary heater, heated windshield washer system and rear heater
7
8 2
4
3 5 2 1
6
3
9
P83.25-2293-00
1 2 3 4
Engine Coolant pump Switchover valve Front heater heat exchanger
5 6 7 8 9
Windshield washer system Stationary heater Rear heater heat exchanger Shutoff valve, AC-side Shutoff valve, engine-side
Vehicle Climate Control - Troubleshooting-Function-Design-Operation - Current Passenger Car Models b
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Knowledge base
Heating circuit
Knowledge base
Explanation of "refrigerant compressor shaft"
Limiter
An initial qualified assessment of the functionality of the refrigerant compressor (A9) can be gained from a visual inspection of the shaft (see diagram). If the shaft does not turn while the engine is running, then the torque limiter is broken and the refrigerant compressor (A9) is defective. In some model series or engine versions, the view of the refrigerant compressor shaft may be obstructed. The shaft can be viewed by lifting the vehicle on a lifting platform or by using additional tools (e.g. mirrors). When doing this, always comply with the regulations governing work in the engine compartment while the engine is running. See Workshop Information System (WIS).
Refrigerant compressor (A9) with marked refrigerant compressor shaft
P83.40-3227-00
Magnetic clutch
Depending on the model series and engine, a refrigerant compressor magnetic clutch (A9y1) may also be installed in addition to the torque limiter. This can be used to completely decouple the refrigerant compressor from the power flow in the belt drive. This provides additional fuel savings. Depending on the version of the refrigerant compressor, the magnetic clutch may be concealed by a protective cover on the end face. A refrigerant compressor with magnetic clutch can be identified by its 4-pin connector plug. Here it is also the case that the refrigerant compressor shaft must turn at the same time when the refrigerant compressor is switched on and the magnetic clutch is operational. See Workshop Information System (WIS).
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Outside temperature sensor value
The sensor value for outside temperature is measured in the area of the front bumper of the vehicle. This means that there are driving situations where the measured value does not correspond to the actual ambient temperature. A good example of this is when the vehicle is driven slowly with a warm engine. In this case, the measured outside temperature value can be significantly higher than the actual ambient temperature. The sensor value is therefore processed for the climate control system under this type of driving condition. This means that in the workshop the processed value for the climate control system does not always match the ambient temperature in the workshop. For some workshop tests (e.g. investigations of climate control comfort) it is therefore necessary to either perform the test outside of the workshop while driving or to drive the vehicle into the workshop with the engine cold (engine temperatures < approx. 40 °C) or to wait until the engine is cold (leave vehicle to cool down overnight).
by the diagnosis system and represents 100% of the possible adjustment range. A large deviation (> 200 steps) indicates that a mechanical problem may be present (e.g. blockage or sluggishness, broken stop or disconnected linkage). The stepper motors can recognize the blockage by the flap stop and report this back to the AC operating unit. Limp-home mode: If a stepper motor is energized but does not receive any messages on the LIN bus for more than approx. 2 s, it switches to limp-home mode. In this case, warm air is blown on to the windshield, the defroster and blend air flaps open and the other flaps are closed at the "zero" position. Once communication with the stepper motors has been restored, the system starts to operate normally again without any further action. The corresponding fault codes will be stored in the fault memory.
LIN stepper motors
LIN stepper motors are installed in model series 169、245, 164, 251, 221, 204 and future model series. They are connected to the AC operating unit via a joint 4-pin (power supply, ground, data input, data output) data line (LIN bus) and receive their adjustment commands from the AC operating unit. Each motor is given a unique separate address during production, which is then stored. If individual addresses are lost or if motors are changed during repairs, the motors must be automatically re-addressed via Star Diagnosis. Before performing automatic addressing ensure that all motors are connected and energized. For the air conditioning to operate properly, the AC operating unit must know the adjustment range of each individual flap on the air conditioner housing. The air conditioning learns the adjustment ranges during normalization. The adjustment range can be read out
Vehicle Climate Control - Troubleshooting-Function-Design-Operation - Current Passenger Car Models b
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Knowledge base
Outside temperature/LIN stepper motors sensor value
Knowledge base
Climate control/heater air ducting
2-zone air conditioning, code 580
Cooling function Air is supplied to the rear seat row via the front air conditioner housing Temperature control of the rear seat row is coupled to that of the front passenger side
P83.40-3770-00
Heating function Air is supplied to the rear seat row via the front air conditioner housing Temperature control of the rear seat row is coupled to that of the front passenger side
P83.25-2289-00
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b Vehicle Climate Control - Troubleshooting-Function-Design-Operation - Current Passenger Car Models
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3/4-zone air conditioning, code 581
Cooling function Air is supplied to the rear seat row via the front air conditioner housing Temperature control of the rear seat row is performed separately
P83.40-3771-00
Heating function Air is supplied to the rear seat row via the front air conditioner housing Temperature control of the rear seat row is performed separately
P83.25-2290-00
Vehicle Climate Control - Troubleshooting-Function-Design-Operation - Current Passenger Car Models b
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3.2/11
Knowledge base
Climate control/heater air ducting
Knowledge base
Climate control/heater air ducting
3/4-zone air conditioning with rear air conditioning, code 582 without rear heater
Cooling function Air is supplied to the rear seat row from the passenger compartment via a separate air intake Temperature control of the rear seat row is performed separately System has a separate refrigeration circuit
P83.40-3772-00
3/4-zone air conditioning with rear air conditioning, code 582 without rear heater
Heating function Air is supplied to the rear seat row from the passenger compartment via a separate air intake Temperature control of the rear seat row is performed separately
P83.25-2291-00
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b Vehicle Climate Control - Troubleshooting-Function-Design-Operation - Current Passenger Car Models
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3/4-zone air conditioning with rear air conditioning, code 582 with rear heater
Cooling function Air is supplied to the rear seat row from the passenger compartment via a separate air intake Temperature control of the rear seat row is performed separately System has a separate refrigeration circuit and separate heating circuit
P83.40-3772-00
3/4-zone air conditioning with rear air conditioning, code 582 with rear heater
Heating function Air is supplied to the rear seat row from the passenger compartment via a separate air intake Temperature control of the rear seat row is performed separately System has a separate refrigeration circuit and separate heating circuit
P83.25-2291-00
Vehicle Climate Control - Troubleshooting-Function-Design-Operation - Current Passenger Car Models b
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3.2/13
Knowledge base
Climate control/heater air ducting
Knowledge base
Stationary heater radio remote control
General
Range The maximum range of the STH radio remote control transmitter (A8/3) is approx. 300 m. The range can be reduced by: • Sources of radio interference • Solid objects between the STH radio remote control transmitter (A8/3) and the vehicle • Unfavorably positioned STH radio remote control transmitter (A8/3) relative to vehicle • Transmitting from closed rooms i Note To achieve the optimal range, the STH radio remote control transmitter (A8/3) must be held vertically upwards during transmission.
Operation via STH radio remote control transmitter (A8/3) with indicator LED (6)
Switching on Press the ON button (3) until the indicator LED (6) in the STH radio remote control transmitter (A8/3) lights up green. Switching off Press the OFF button (2) until the indicator LED (6) in the STH radio remote control transmitter (A8/3) lights up red. LED displays of STH radio remote control transmitter (A8/3) • Indicator LED (6) continuously on for two seconds in green or red (green for switch-on, red for switchoff): Wireless connection to the vehicle was properly established. • Indicator LED (6) flashing for two seconds in green or red (green for switch-on, red for switch-off): Wireless connection to the vehicle was not established. • Indicator lamp (6) continuously on for two seconds in orange before the green or red signal (regardless of whether flashing or continuous): The transmitter battery is weak but transmitter can still transmit. • Indicator lamp (6) flashes orange for five seconds: The transmitter battery is too weak to transmit.
T70
P83.70-5018-00
T90 1 2 3 6 A8/3
P83.70-5184-00
Antenna OFF button ON button Indicator LED STH radio remote control transmitter
3.3/1
b Vehicle Climate Control - Troubleshooting-Function-Design-Operation - Current Passenger Car Models
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Operation via STH radio remote control transmitter (A8/3) with display (5)
i Note If the battery of the STH radio remote control transmitter (A8/3) is weak, a battery symbol appears on the right of the display (5).
i Note For the first time as of model series 221/216, 204, 207 and 212, the departure time and not the starting time of the stationary heater is entered on the instrument cluster or remote control.
1 2 3 4 5 A8/3 Antenna OFF button ON button Call up status or set departure time Display STH radio remote control transmitter
P83.70-5019-00
Switching on Press the ON button (3) on the STH radio remote control transmitter (A8/3). Possible feedback Display Meaning The stationary heater is switched on.
Switching off Press the OFF button (2) on the STH radio remote control transmitter (A8/3). Possible feedback
Signal transmission between radio remote control and stationary heater is faulty.
Display
Meaning The stationary heater is switched off.
Heating is not possible. There is a fault in the heater unit or there is insufficient fuel in the fuel tank.
Signal transmission between radio remote control and stationary heater is faulty.
Faulty signal transmission to stationary heater control unit or vehicle battery is not sufficiently charged.
Vehicle Climate Control - Troubleshooting-Function-Design-Operation - Current Passenger Car Models b
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Knowledge base
Stationary heater radio remote control
Knowledge base
Stationary heater radio remote control
Check status of stationary heater Press left or right button (4). Depending on the operating state of the stationary heater, one of the following messages appears on the display (5) of the STH radio remote control transmitter (A8/3).
Possible displays Display Meaning The stationary heater is switched off. Display Meaning The stationary heater is switched on. The number in the display of the radio remote control indicates the remaining heating time. A departure time is selected. The time on the display indicates the departure time.
Signal transmission between radio remote control and stationary heater is faulty.
As of model series 221/ 216
Faulty signal transmission to stationary heater control unit, the vehicle battery is not sufficiently charged, tank not sufficiently full (for heating) or system fault.
As of model series 221/ 216
A departure time is selected. The stationary ventilation is currently active. The time on the display indicates the departure time.
The stationary ventilation is switched on. The number in the display of the radio remote control indicates the remaining ventilation time.
As of model series 221/ 216
A departure time is selected. The stationary heater is currently active. The time on the display indicates the departure time.
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b Vehicle Climate Control - Troubleshooting-Function-Design-Operation - Current Passenger Car Models
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Query status of departure time (as of model series 204, 207, 212, 221/216) The departure times are shown when a status query is made and in the sequence shown in the diagram below when the left or right button (4) is pressed again. The "X" symbol and the departure time appear for each respective departure time.
Display OFF
Timeout
Button "<" or ">"
Status indicator
">" "<"
Departure time 1
">" "<"
Departure time 2
">" "<"
Departure time 3
">"
Vehicle Climate Control - Troubleshooting-Function-Design-Operation - Current Passenger Car Models b
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3.3/4
Knowledge base
Stationary heater radio remote control
Knowledge base
Stationary heater radio remote control
Activate set departure time (as of model series 204, 207, 212, 221/216) • Press the left or right button (4) on the STH radio remote control transmitter (A8/3) until the desired departure time appears on the display (5). • Press the ON button (3) on the STH radio remote control transmitter (A8/3). The "X" symbol and the departure time appear on the display (5). i Note To activate the departure time the vehicle must be within radio range otherwise "¢ FAIL" appears on the display when the buttons are pressed. If the vehicle is in range, the symbols and digits described in the text appear.
Wireless connection to vehicle Status query ">"
"<" Activate ON button
Departure time 1
X
8:15
"<" ">"
Departure time 2
X 12:15
"<" ">"
See departure time 1
Departure time 3
X 21:15
See departure time 1
">"
3.3/5
b Vehicle Climate Control - Troubleshooting-Function-Design-Operation - Current Passenger Car Models
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Deactivate set departure time (as of model series 204, 207, 212, 221/216) Press the left or right button (4) twice on the STH radio remote control transmitter (A8/3) to call up a departure time. Press the OFF button (2) on the STH radio remote control transmitter (A8/3). The "OFF" symbol appears on the display (5). The active departure time is deactivated.
i Note The active departure time is deactivated by pressing the OFF button (2) regardless of which departure time is selected in the menu.
Wireless connection to vehicle Status query ">"
"<" Deactivate OFF button
Departure time 1
X
8:15
"<" ">"
Departure time 2
X 12:15
"<" ">"
See departure time 1
Departure time 3
X 21:15
See departure time 1
">"
Vehicle Climate Control - Troubleshooting-Function-Design-Operation - Current Passenger Car Models b
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3.3/6
Knowledge base
Stationary heater radio remote control
Knowledge base
Stationary heater radio remote control
i Note The "Set departure time" function is only possible as of model series 204, 207, 212, 221/216. i Note • The longer the left or right button (4) is held down, the faster the displayed time changes. • To set the departure time the vehicle must be within radio range otherwise "RADIO FAIL" appears on the display when the buttons are pressed. If the vehicle is in range, the symbols and digits described in the text appear.
Set departure time (as of model series 204, 207, 212, 221/216) • Press the left or right button (4) on the STH radio remote control transmitter (A8/3) until the time to be adjusted is selected. • Press the ON button (3) and OFF button (2) simultaneously on the STH radio remote control transmitter (A8/3). The "X" symbol flashes on the display (5) on the STH radio remote control transmitter (A8/3). • Set the desired departure time with the left or right button (4) on the STH radio remote control transmitter (A8/3). • Press the ON button (3) and OFF button (2) simultaneously on the STH radio remote control transmitter (A8/3). The new departure time is stored.
Status query
">"
Store 8:23
Wireless connection to vehicle
Store ON and OFF button "<" Set ON and OFF button Abort Timeout See departure time 1
Departure time 1
X
8:15
X
8:23
"<" ">"
Departure time 2
X 12:15
"<" ">"
Departure time 3
X 21:15
See departure time 1
">"
3.3/7
b Vehicle Climate Control - Troubleshooting-Function-Design-Operation - Current Passenger Car Models
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The following pages provide important information and background knowledge concerning common air conditioning-related complaints associated with this vehicle model. The keywords are highlighted for clarity.
Odor from air conditioning The complaint "Damp air or odor of laundry just after engine start" is due to physical laws. Fluid that accumulates at the evaporator during operation is absorbed by the air in the evaporator housing when the blower is shut off. When the blower is activated again, this damp air is carried into the interior compartment within the first few minutes. Repairing or replacing components does not remedy the problem. This should be explained to the customer. In the event of odor-related complaints, make sure that there are no objects or dirt in the vehicle that might be causing the odors (luggage compartment, under the seats and floor mats, ashtray, stowage compartments). Furthermore, when air recirculation is active, odors from dirt on shoes or floor mats may be drawn in and circulated in the interior compartment by the blower. Refer to the "A/C Check" to identify the source of the odor. In this context also refer to the note "Automatic air recirculation". Sporadic odors may be caused by temporary environmental influences such as exhaust gases from other vehicles, tunnels, agriculture etc. Fogged windows Possible causes for windows fogged on the inside may be: • Damp in the interior (check floor mats and carpeting) • Dirty windows promote window fogging so it is important to keep the windows clean (inside and outside). • Driving with air conditioning deactivated (explain to the customer that this does not save fuel because the air conditioning systems in current model series feature volume-controlled refrigerant compressors) • Badly set air outlets/flaps (particularly the center air outlets, side air outlets, and defroster outlets). The air flow should be directed onto the fogged areas (see FlashFog logic). • Fouled filters • Driving with air recirculation activated (exacerbated by having the air conditioning off) • Refrigerant compressor shutoff (engine emergency off, anti-icing protection, consumer shutoff) Possible causes for windows fogged on the outside may be: • Positions of center air outlets (diffuse field) or other flap positions. The air flow should be directed away from the fogged areas.
Vehicle Climate Control - Troubleshooting-Function-Design-Operation - Current Passenger Car Models b
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1.1/1
Model 221.095/195 (S-Class Hybrid)
Model-specific information (climate control complaints)
Model 221.095/195 (S-Class Hybrid)
Model-specific information (climate control complaints)
Saving fuel by driving with the air conditioning deactivated Consumption-optimized refrigerant compressors are used on all current model series i.e. they are only actuated according to demand. Due to the required cooling of the high-voltage battery module, the climate control system has to be kept operating in most circumstances on vehicles with hybrid technology. Therefore, switching off the air conditioning when outside temperatures are low has only a very slight influence on fuel economy, but can encourage fogged windows or odors from the evaporator. Advise the customer to leave the air conditioning switched on all the time. Differences between "identical" vehicles Due to the variety of different versions and new features introduced in the course of each year, differences in the control logic are highly probable. Furthermore, the codings may vary, meaning that fundamentally different control logic systems are involved. For this reason we strongly discourage the use of reference vehicles. This should also be pointed out to the customer if necessary. Differences in new vehicles of existing owners Existing customers with new vehicles should be advised that the functions of the air conditioning can change with every modification year. It is therefore highly likely that functions with which the customer was familiar from his old car have changed in his new vehicle. This should be explained to the customer when selling the vehicle or when complaints are received! Faults do not usually exist with this kind of complaint. Reaction time of air conditioning Air conditioning systems require a certain amount of time to regulate the set temperature. Give the air conditioning time to stabilize properly. A drastic manual increase or reduction in the temperature or blower stage (e.g. when starting up and in extreme outside temperatures) does not normally produce quicker reactions. Differences of "DEFROST" function" Depending on the vehicle model, the powerplant and the modification year in question, there may be differences in the control/actuation of the blower when "DEFROST" is activated. What is more, differences in control are possible in the same vehicle because, depending on the engine heat output, the ambient conditions and other influencing factors, the best possible control curve can be selected in order to deice the windows as quickly as possible. Control differences Reactions to changes in the target temperature on the operating unit may vary considerably from vehicle to vehicle depending on the engine heat output, the ambient conditions and other influencing factors. In each case the control unit selects an optimized control curve to achieve the best possible adaptation. For example, it is possible to change only the outlet temperature of the air without changing the blower stage. Similarly, open windows, doors and sliding roof or Vario roof can cause differences in the control of the air conditioning in certain vehicles.
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b Vehicle Climate Control - Troubleshooting-Function-Design-Operation - Current Passenger Car Models
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Implausible regulation – single/multiple-zone sun sensor Multiple-zone sun sensors have a substantial influence on temperature control. When the sunlight hits the vehicle at an angle, this may result in extreme differences in the outlet air temperatures and blower outputs between the left and right sides. This effect can also occur under cloudy skies due to UV radiation. The sensitivity of the sun sensor can be coded with Xentry Diagnostics (XD)/Xentry DAS. Implausible regulation – outside temperature indicator temperature sensor If you cannot understand why the climate control is operating in a certain way, the outside temperature indicator temperature sensor (B14) should also be taken into account. Through a simple plausibility check (e.g. comparison of outside temperature value shown on instrument cluster) while driving when the complaint occurs, it is possible to rule out the possibility that the control unit of the air conditioning is receiving an incorrect outside temperature value and thus regulating incorrectly. Weather-related effects (e.g. due to snow and ice) or mechanical impairment (e.g. a sensor unclipped by a foreign object) must also be considered. You should also take the information in the model series-specific "Climate control functions" section under the "Outside temperature" point into account. Implausible regulation on model series with several interior temperature sensors In the event of implausible regulation or nonfunctional components: check interior temperature sensors present.
Temperature differences Temperature differences between the driver and front passenger side are normal in certain model series and should be compensated for by regulating the operating unit manually. Temperature differences between left and right Warning for air-regulated systems: In the event of temperature differences between left/right do not replace the shutoff valve. Separate valves (pulsed valves) for the left and right sides exist only in waterregulated systems. Poor control quality/temperature differences/ intermittently too hot or too cold/cold feeling The customer complaint "poor control quality/ temperature differences/intermittently too hot or too cold/cold feeling" may be caused by leakage in the bodywork. This applies above all when the complaint occurs in conjunction with abrupt vehicle speed changes (e.g. braking after driving fast). Temperature differences/blower output occasionally too warm The customer complaint "Temperature differences/ blower output occasionally too warm" can be due to temporary limitation of the output of the electric refrigerant compressor. Please note that output limitation of the electric refrigerant compressor does not cause a fault memory entry because it is a normal and necessary protection function of the battery management system. Replacing parts does not remedy the problem. Refer to the note "Consumer shutoff".
Vehicle Climate Control - Troubleshooting-Function-Design-Operation - Current Passenger Car Models b
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1.1/3
Model 221.095/195 (S-Class Hybrid)
Model-specific information (climate control complaints)
Model 221.095/195 (S-Class Hybrid)
Model-specific information (climate control complaints)
Cold feeling after driving for a long time The customer complaint "cold feeling after driving for a long time" is usually due to subjective sensations or settings on the air conditioning. The cause of the customer complaint "cold feeling after driving for a long time" is a natural reaction of the body, which adopts a state of rest after long periods without physical exertion and produces less heat. Since freedom of movement is severely restricted inside the vehicle, the blood flow in the legs especially is impaired. The result is inadequate blood circulation, which can lead to a "cold feeling" in the legs. If the customer complains of a "cold feeling after driving for a long time", advise them to adjust the temperature of the air conditioning manually to suit their needs and on long journeys to take regular breaks with physical exercises (rule of thumb: every 200 kilometers or every two hours). Also check the settings for the rear blower (cold air in the rear compartment can travel into the front footwells.) "Cold feet" (with code 582 Rear air conditioning) If the customer complains of "cold feet", first check the settings in the rear compartment. If the rear is set to "cooling", it can happen that the cold air travels forwards from the rear under the seats. No or poor heat output Depending on the engine model installed, this may be caused by the heating system shutoff valve (Y16/2) at the engine. This valve is controlled via the engine control unit. Please check accordingly. Poor heat output/cooling output in rear The control response in the rear can be delayed because the air or hot water (with code 582 Rear air conditioning) has to travel a longer distance from the front air conditioner housing or engine to the rear air vents and can thus cool down or heat up on the way. Cold feeling at the rear/no heating at the rear (without code 582) The rear center air outlet always takes its air from the coolest point. For this reason cool air emerges from the rear center air outlet even when heating mode is active at the front. In the case of this complaint it is advisable to close the rear center air outlet. Warmer air is then supplied via the rear footwell air outlets and also via the B-pillar on model 221. Replacing parts does not remedy the problem. Knocking noises from pulsed valves (with code 582) Knocking noises in model series with water-regulated air conditioning systems, as with this rear air conditioning system (see chapter "Knowledge base"), are normal. The noises are caused by the pulsed valves. In residual heat mode these noises are more obvious because they are normally overlaid by other noise sources while driving. Replacing parts does not remedy the problem. Rear air conditioning nonfunctional (all model series with code 582) Check and, if necessary, replace the rear refrigeration circuit shutoff valve (Y67). The filter may be clogged. When removed, visually inspect for shavings and dirt.
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b Vehicle Climate Control - Troubleshooting-Function-Design-Operation - Current Passenger Car Models
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Sound level of electric refrigerant compressor Due to the low engine sound level and automatic engine stops, isolated customer complaints are received about the sound level of the electric refrigerant compressor. Up to a refrigerant compressor speed of approx. 3000 rpm, the sound level is perceived as a "non-distracting buzzing sound" but above this speed the sound level is somewhat higher and audible from the outside. If the electric refrigerant compressor is producing a different sound level, the refrigerant compressor may not be supplying its full output during control operations. By checking the condition (coloration, residues from mechanical wear) of the refrigerant and refrigeration oil, it is possible to rule out the possibility that the electric refrigerant compressor is mechanically damaged and thus causing excessive noise. Replacing parts without prior inspection will not rectify the problem. Flow noises/whistling noises in the interior at high vehicle speeds At higher speeds and with the flaps in certain positions, there may be turbulence in the air stream which may cause flow noises. Possible remedy: code speeddependent recirculated air via Xentry Diagnostics (XD)/Xentry DAS.
More air from one outlet than from others If the customer complains of "more air from one outlet than from others", note that when some air outlets are closed, the air flow is distributed among the remaining outlets in the vehicle and this can result in air flows of varying intensity. The climate control can also create such differences intentionally (e.g. to compensate for the angle of the sun). No air or insufficient air emerging although the blower is running If the blower is running but there is no air at any outlet, this can be an indication of icing in the evaporator. This symptom disappears when the vehicle and the engine are left off for a certain time (the ice at the evaporator thaws). To rule out the possibility of a defective evaporator temperature sensor (B10/6), also check the evaporator temperature sensor (B10/6) for plausibility using Xentry Diagnostics (XD)/Xentry DAS for this customer complaint. No blower setting bars on the display in "DEFROST" or "REST" mode Depending on the model year, when the "DEFROST" or "REST" function is activated the blower setting bars on the display disappear and a fixed blower setting and temperature are set. As long as this function is active, the customer will not be able to intervene in the control process.
Vehicle Climate Control - Troubleshooting-Function-Design-Operation - Current Passenger Car Models b
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1.1/5
Model 221.095/195 (S-Class Hybrid)
Model-specific information (climate control complaints)
Model 221.095/195 (S-Class Hybrid)
Model-specific information (climate control complaints)
"AC-OFF" in central climate control menu on the COMAND display cannot be deactivated The complaint "AC-OFF in central climate control menu on the COMAND display (A40/8) or on the SPLITVIEW display (A40/10) (with code 867) cannot be deactivated" indicates that the air conditioning system is empty or not sufficiently full. The refrigerant compressor has been shut off for its own protection. The detailed procedure can be found in WIS under "Empty/evacuate/refill air conditioning and check for proper operation and leaks" (AR83.30-P-1760SX). Air conditioning switches on automatically When the high-voltage battery module requires cooling, the battery management control unit issues a cooling request. This can result in the electric refrigerant compressor starting up audibly e.g. with the start/stop function active. The air conditioning operates with the same settings prior to it being switched off. Air conditioning cannot be switched off If the high-voltage battery module still requires cooling, the air conditioning cannot be shut off (disable function: the deactivation is reversed after 2 s). The air conditioning remains switched on after the battery is cooled. Noises after switching off If the customer complains about "whistling or hissing noises after switching off", point out that these can be produced by the equalization of gas pressure at the expansion valve. These noises can even occur a long time after the vehicle is switched off. Other noises after switching off can be caused by actuator motors moving into their park position (as much as several minutes after switching off the ignition). Replacing parts does not remedy the problem.
1.1/6
b Vehicle Climate Control - Troubleshooting-Function-Design-Operation - Current Passenger Car Models
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The following pages provide important information and background knowledge concerning climate control functions on this vehicle model.
Automatic air recirculation Automatic air recirculation is not indicated by the function LED. Depending on the equipment installed, automatic air recirculation is activated e.g. in the case of high outside temperatures or poor quality of the fresh air (pollutants). Automatic air recirculation is not possible when the following settings are active: • Air conditioning deactivated (note control logic of A/C – ACOFF buttons) • Maximum heating • DEFROST • In cold temperatures (only at temperatures above approx. 5 °C, even if the activated charcoal filter is activated) The sensitivity of the pollutant sensor changes according to the ambient conditions. For this reason, exhaust odors after driving for a long time under identical environmental conditions may be normal. Air recirculation flap closes when air conditioning is switched off When the air conditioning is switched off using the "0 button" or the blower is set to "0" (depending on equipment installed), the air recirculation flap is closed. The function can be set via Xentry Diagnostics (XD)/Xentry DAS. Reduction of door closing forces through flap adjustment When the ignition is off and one of the doors is opened, the fresh air/recirculated air flap and the ram air flap (with code 581) are partially opened by the fresh air/recirculated air/ram air flap actuator motor. This reduces the door closing forces. The function can be set via Xentry Diagnostics (XD)/Xentry DAS. Convenience closing Convenience closing (tunnel mode switching) is only possible provided that all the windows and the tilting/ sliding roof (if installed) are normalized. If necessary, normalize the components with Xentry Diagnostics (XD)/Xentry DAS. If the air recirculation mode button is pressed briefly after convenience closing has occurred, the previously stored positions (windows, sliding roof) are lost. In vehicles fitted with activated charcoal filter button, this can also be used to operate the convenience closing feature. For a detailed description of the "convenience closing" function, refer to the explanation of the "air recirculation mode button" in the relevant model description.
Vehicle Climate Control - Troubleshooting-Function-Design-Operation - Current Passenger Car Models b
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1.1/7
Model 221.095/195 (S-Class Hybrid)
Model-specific information (climate control functions)
Model 221.095/195 (S-Class Hybrid)
Model-specific information (climate control functions)
FlashFog logic To prevent windows from fogging up, no air is directed at the windshield for a short time after engine start. This function cannot be prevented even by adjusting the flaps manually. Only the defrost function disables the FlashFog feature. The duration of this function can vary depending on the model series and the ambient conditions. In the event of complaints, this should be explained to the customer. Defrost function When the Defrost function is activated, the refrigerant compressor is actuated to dry the air as effectively as possible. Anti-icing protection To prevent the refrigerant compressor from icing up, the values from the evaporator sensor are checked constantly while the air conditioning is operating. If the values approach the 0 °C limit, the control unit turns down the refrigerant compressor in order to prevent icing. This produces temperature fluctuations/surges at the evaporator sensor which may be perceived by sensitive customers. Please note that the anti-icing protection of the refrigerant compressor does not cause a fault memory entry because it is a normal and necessary protection function of the air conditioning system. Replacing parts does not remedy the problem. Evaporator drying (as of 14.9.2010) In order to counteract odors from the evaporator in the interior compartment and prevent fogging of the windows when the air conditioning starts up, the evaporator of the air conditioning system is dried. One hour after the engine is shut off, the instrument cluster transmits the request to dry the evaporator to the AAC [KLA] control and operating unit via interior CAN, which initiates drying of the evaporator. To do so, the blower is activated at its lowest stage for 30 min. This coding is coded to "active" or "not active" at the plant depending on the country of sale. Cold start lockout The cold start lockout function prevents a high blower speed from being set in cold outside temperatures. This function is purely for the customer's comfort. As the temperatures in the heating circuit rise, the blower speed setting is increased. Center air outlet In cold outside temperatures or in heating mode the center air outlet can be closed automatically by the air conditioning control unit in order to improve comfort levels. Because warm air rises, this results in more uniform heating of the interior compartment.
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b Vehicle Climate Control - Troubleshooting-Function-Design-Operation - Current Passenger Car Models
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Air Ducting On model series 221/216, the air distribution can be changed either using the buttons in the upper control panel or electronically via the central display. Blower lowering via voice control system (VCS) With the voice control system active, the blower output is limited to 50%. To do so, the radio and navigation unit or the COMAND controller unit transmits the status of the voice control system to the automatic air conditioning control and operating unit via interior CAN. This then limits the blower output. Consumer shutoff Most Mercedes-Benz vehicles feature a consumer shutoff function. If the on-board power supply voltage is too low, e.g. when several consumers are switched on just after moving off or when the engine is idling, certain convenience functions may be stepped down or shut off entirely. These functions include the vehicle climate control, the "residual heat" blower control (can also be shut off while stationary) and the stationary heater or heater booster (PTC). Although an increase in the blower stage can be seen on the display in the case of a temporary consumer shutoff, the blower itself does not react. Likewise it is possible that the rear window heater may not start up even though it has been activated and activation is confirmed by the lighting of the function LED on the operating unit. A fault is not stored in the case of a temporary consumer shutoff. When these complaints are encountered, it is therefore absolutely essential to find out the precise ambient and driving conditions that existed at the time the complaint occurred.
Actuation of rear window heater In all model series apart from model series 164/251, the rear window heater is regulated by the rear SAM and not by the AC operating unit. However, in all models the rear SAM receives and passes on the "rear window heater" signal (including model series 164/251). For this reason, it is absolutely essential to check the rear SAM component as well in the case of a malfunction of the rear window. Switch-on time of rear window heater The rear window heater does not switch on immediately after actuation of the corresponding switch on the AC operating unit at extremely low outside temperatures. In order to provide the best possible window deicing performance, the rear window heater is only activated above a certain interior temperature when outside temperatures are extremely cold. However, the function LED in the operating unit lights up immediately the button is pressed. Similarly, the heating duration of the rear window heater (automatic shutoff) can vary depending on the outside temperature and other ambient conditions. Refer to the note "Consumer shutoff". These control features are intentional. Please explain this logic to the customer. Replacing parts does not remedy the problem.
Vehicle Climate Control - Troubleshooting-Function-Design-Operation - Current Passenger Car Models b
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1.1/9
Model 221.095/195 (S-Class Hybrid)
Model-specific information (climate control functions)
Model 221.095/195 (S-Class Hybrid)
Model-specific information (climate control functions)
Actuation of electric refrigerant compressor The electric refrigerant compressor is not actuated directly by the AAC [KLA] control unit and can be actuated by two different events: • Interior climate control request: The AAC [KLA] control unit transmits a cooling request via interior CAN (CAN B) to the central gateway (CGW) control unit. This routes the request via chassis CAN (CAN E) to the ME-SFI [ME] control unit. The ME-SFI [ME] control unit then actuates the electric refrigerant compressor via the drive train sensor CAN (CAN I). • High-voltage battery module cooling request: The battery management control unit transmits a cooling request via ME-SFI [ME] and CGW to the AAC [KLA] control and operating unit. Please refer to the data flow charts and block diagrams in the relevant model descriptions. Air conditioning starts up with a delay Under certain circumstances, temperature changes when the vehicle is parked (e.g. day/night differences) may cause the refrigerant compressor to start up with a delay when the engine is started. This is due to natural causes. Repairing or replacing components does not remedy the problem. ACOFF in central display On model series 221/216 there is, for the first time, no switch in the upper control panel for activating/ deactivating the refrigerant compressor. The system is activated/deactivated electronically via the central display. Outside temperature value Outside temperature indicator temperature sensor (B14): The outside temperature value is stored as soon as the vehicle travels slower than 30 km/h. This value is adjusted in stages only when the vehicle travels faster than 30 km/h for a certain length of time. When the vehicle is stationary, therefore, a plausibility check of this sensor value using Xentry Diagnostics (XD)/Xentry DAS is not meaningful because only the stored value for the outside temperature can be retrieved. There is no possibility to reset the stored outside temperature value. Should you encounter complaints concerning the temperature control which cannot be reproduced while stationary, we recommend that you attempt to reproduce the complaint under the conditions described by the customer (see reception protocol). Rear air conditioning systems (with code 582) Rear air conditioning systems only draw in interior air (please note this in the event of odor-related complaints).
1.1/10
b Vehicle Climate Control - Troubleshooting-Function-Design-Operation - Current Passenger Car Models
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The following pages provide important information and background knowledge concerning repairs to air conditioning systems on this vehicle model.
Work on vehicles with high-voltage on-board electrical system Personnel who perform repair, maintenance and diagnosis activities on vehicles with high-voltage on-board electrical systems must have completed a special course of qualification. (awareness course for highvoltage on-board electrical systems). A special electrical qualification and authorization are essential for personnel who de-energize the highvoltage on-board electrical system before work on vehicles with a high-voltage on-board electrical system and perform the subsequent initial startup process. Persons who have not completed a special qualification course and have neither special electrical training nor authorization may not carry out work on highvoltage on-board electrical systems. Work on the refrigeration circuit Even among vehicles of the same model series the AC lines installed may be of different diameters. When carrying out repairs, make sure that the correct tool sizes (e.g. service valves) are used. Maintenance/repair work on the refrigeration circuit When carrying out maintenance/repair work on the refrigeration circuit, make sure that the system is not opened for longer than 15 minutes. In all other cases please use the specified couplings and stop plugs to keep the circuit closed (see AH83.30-N-0005-01A). Replacement of refrigeration circuit components WIS contains a detailing listing of filling capacities and the amounts of oil to be added to the refrigeration circuit for a complete refill when components are replaced (see BF83.00-Z-9999AZ). Refrigerant compressor replacement When replacing a refrigerant compressor, always make sure that metal shavings and other foreign particles are not left behind in the refrigerant circuit as these may cause renewed problems with the new refrigerant compressor (see AR83.30-P-1782A). Compressor damage Actuating the refrigerant compressor when the system has been evacuated causes serious defects. The compressor is not lubricated and is worn out.
Vehicle Climate Control - Troubleshooting-Function-Design-Operation - Current Passenger Car Models b
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1.1/11
Model 221.095/195 (S-Class Hybrid)
Model-specific information (climate control repairs)
Model 221.095/195 (S-Class Hybrid)
Model-specific information (climate control repairs)
Refrigerant compressor nonfunctional/ presumably defective Since the electric refrigerant compressor is supplied with power by the high-voltage on-board electrical system and does not have its own fault memory, all fault memory entries of the engine control unit and battery management control unit must be processed as per Xentry Diagnostics (XD)/Xentry DAS in the event of function complaints. Another basic requirement is a fully operational power supply to the electric refrigerant compressor. As a result, all electrical lines, connectors and ground points must be checked for damage and corrosion. Also refer to the information about "Working on vehicles with high-voltage on-board electrical system". Implausible pressures at the high and low-pressure side Feel the entire line system and look for noticeable temperature differences, a sign of clogged lines. Air conditioning nonfunctional Sensors and actuators networked over the AC bus (e.g. the sun sensor or stepper motors) can disable the function of the entire AC bus if they develop a fault. Diagnostic mode In most model series the air recirculation button flashes in diagnostic mode (not to be confused with shutoff due to lack of refrigerant). This is not a fault, it indicates diagnostic mode with Xentry Diagnostics (XD)/Xentry DAS is connected. In model series 169/245 the diagnostic mode is not displayed. Bus faults When bus faults are detected by Xentry Diagnostics (XD)/Xentry DAS, the system must be activated without sensors and the component causing the problem must be found by reconnecting the components individually. All fault codes must be erased before each new test. Erasing AC bus faults Some faults on the AC bus are only erased after ignition OFF. (For an overview of the AC bus, see System overview/block diagram). LIN bus On vehicles with LIN bus communication (see chapter "Knowledge base") note the following: Components that communicate with each other via LIN bus are switched one behind the other in series. If a sensor or actuator is defective, all the components connected downstream of it no longer function because they can no longer be actuated, or they switch to limp-home mode. Limp-home can also be actuated if the blower regulator detects a disruption in communications. If the ground connection is defective or there is a short circuit in a LIN bus component, a fault code may be stored for all the components connected to the bus. In the event of a defect or malfunction on the LIN bus, check all the components connected to the LIN bus in their proper sequence before replacing individual parts. Refer to the block diagram.
1.1/12
b Vehicle Climate Control - Troubleshooting-Function-Design-Operation - Current Passenger Car Models
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Failure of the LIN bus A short to ground or short circuit in the LIN bus results in a total failure of the LIN bus. In the event of a total failure or malfunction on the LIN bus, check whether water damage has caused the failure of the air distribution actuator motors in the Bpillar. Coding The function of the air conditioning may also be influenced by codings in control units outside the air conditioning system (e.g. SAM, EZS, engine control unit, battery management control unit etc.). All control units are SCN-coded and thus preset/fused at the plant. Modifications cannot be made manually or must only be carried out after consultation with the respective MPC. Please refer to the data flow charts and block diagrams in the relevant model descriptions. Blower actuation in event of undervoltage (consumer shutoff) In the event of undervoltage, actuation of the blower is limited without a fault entry being made, mainly with the engine off (lower limit is 50% of blower output). Blower motor or blower regulator In the event of problems with the blower motor or blower regulator, check the parts one by one to ascertain which of the components is actually defective.
Operating unit replacement If replacement of the operating unit is unavoidable, please be sure to order the correct replacement part. Note any changes in the control and regulation logic. Check the codings before replacing the unit. When replacing operating units in particular, please note that there may be differences in the control logic and expressly advise the customer of this. Before replacing an operating unit, always perform a circuit 30 reset in order to check the function. Rear operating units Strictly speaking, rear operating units in vehicles with code 581 are merely switches and display elements with no control logic, which forward the signals to the front air conditioning control unit or display them. Replacement does not provide a remedy for problems with temperature adjustment or air ducting (exception: button or contact faults). Rear operating unit is separate control unit (all model series with code 582) On vehicles with rear air conditioning with code 582, the rear operating unit is a separate control unit which is responsible for controlling and actuating the rear air conditioning.
Vehicle Climate Control - Troubleshooting-Function-Design-Operation - Current Passenger Car Models b
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1.1/13
Model 221.095/195 (S-Class Hybrid)
Model-specific information (climate control repairs)
Model 221.095/195 (S-Class Hybrid)
Climate control operation
Automatic air conditioning as of 06/2008
Upper control panel control unit (N72/1)
P54.21-3215-00
Rear air conditioning operating unit with code 582
Rear air conditioning control unit (N22/4)
P83.50-2139-00
1 2 3 4 5 6 9
Temperature selector paddle Blower stage paddle Defroster button Air recirculation mode button Rear window heater button AUTO button OFF button
10 12 13 14 15 16
REST button Rear temperature selector paddle Rear air distribution button Rear blower stage/REST button OFF/AUTO/Manual button Rear display
2.1/1
b Vehicle Climate Control - Troubleshooting-Function-Design-Operation - Current Passenger Car Models
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Control options
The automatic air conditioning can be operated via the COMAND controller unit (A40/3) or via the buttons of the upper control panel control unit (N72/1). The rear air conditioning is also operated via the COMAND controller unit (A40/3) or via the buttons of the rear air conditioning control unit (N22/4). Temperature selector paddle (1) Pressing the appropriate temperature selector paddle (1) sets the desired target temperature. Blower stage paddle (2) The relevant blower stage paddle (2) is used to set the blower stages manually. Defroster button (3) When the defroster button (3) is pressed, the temperature is increased relative to the ambient temperature and the air flow is distributed to the defroster and side air outlets. All the other flaps are closed. The blower output is regulated in relation to the coolant temperature. When defroster mode is activated, the function LED in the button lights up. Air recirculation mode button (4) A quick press of the air recirculation mode button (4) closes the fresh air flap. This causes the air to circulate in the interior compartment only. The function LED in the button lights up during air recirculation mode. Another quick press of the button opens the fresh air flap and the function LED goes out. Air recirculation convenience feature When the air recirculation mode button (4) is held down for more than 1.5 s, the convenience closing function of the windows or the tilting/sliding roof (code 414) or the top sliding roof (code 413) is activated. When the button is held down again for more than 1.5 s, the components automatically return to their original positions. Rear window heater button (5) Pressing the rear window heater button (5) switches on the rear window heater and the function LED in the button lights up. Pressing the button again switches the rear window heater back off and the function LED goes out. The rear window heater switches itself off automatically after a short time. The heating time depends on the outside temperature, the interior temperature and the driving conditions.
i Note The manual air distribution function and the ACOFF function cannot be set using the buttons on the upper control panel control unit (N72/1). These functions can only be set via the COMAND controller unit (A40/3).
i Note Even when the rear window heater button (5) has been pressed and the function LED has lit up, there may be a delay before the rear window heater starts up. Activation of the rear window heater depends on the detected interior temperature.
Vehicle Climate Control - Troubleshooting-Function-Design-Operation - Current Passenger Car Models b
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2.1/2
Model 221.095/195 (S-Class Hybrid)
Climate control operation
Model 221.095/195 (S-Class Hybrid)
Climate control operation
AUTO button (6) When the relevant AUTO button (6) is pressed, the air flow and air distribution are regulated automatically. When automatic mode is activated, the function LED in the button lights up. When the automatic function is deactivated via the AUTO button (6), both the blower and the air distribution change back to static set values. Rear temperature selector paddle (12) Pressing the appropriate rear temperature selector paddle (12) sets the desired target temperature in the rear compartment. The selected value is shown in the rear display (16). Rear air distribution button (13) Pressing the relevant rear air distribution button (13) directs the air manually to the various areas of the rear compartment. The selected air distribution is shown by corresponding symbols in the rear display (16). Rear blower stage/REST button (14) Pressing the rear blower stage/REST button (14) adjusts the rear blower manually in stages. The set blower stage is shown by corresponding symbols in the rear display (16). The residual heat function can only be activated when the ignition is switched off. Pressing the rear blower stage/REST button (14) activates heating or ventilation only for up to 30 min more. If the on-board power supply voltage is too low, the residual heat function is switched off automatically. When residual heat mode is activated, the "REST" symbol appears in the rear display (16).
i Note While in automatic mode, if the blower is adjusted manually with the blower stage paddle (2) or the air distribution is changed manually via the COMAND controller unit (A40/3), automatic mode is deactivated and the function LED goes out. OFF button (9) Pressing the OFF button (9) switches off the automatic air conditioning and the function LED in the button lights up. When the button is pressed again, the automatic air conditioning is switched on and the function LED goes out. REST button (10) The residual heat function can only be activated when the ignition is switched off. Pressing the REST button (10) activates heating or ventilation only for up to 30 min more. If the on-board power supply voltage is too low, the residual heat function is switched off automatically. When residual heat mode is activated, the function LED in the button lights up. Pressing the button again switches residual heat mode back off and the function LED goes out.
2.1/3
b Vehicle Climate Control - Troubleshooting-Function-Design-Operation - Current Passenger Car Models
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OFF/AUTO/Manual button (15) Pressing the OFF/AUTO/Manual button (15) selects between automatic and manual modes, and switches the rear air conditioning on and off. In automatic mode the blower output and the air distribution at the rear are regulated automatically. When automatic mode is activated, a dot appears in front of the "AUTO" symbol in the rear display (16). In manual mode the blower is adjusted manually via the rear blower stage/REST button (14). The air distribution is directed to the selected areas of the vehicle with the rear air distribution button (13). A dot appears in front of the "MAN" symbol in the rear display (16) and the set blower stage and air distribution are shown.
Rear display (16) The rear display (16) provides information about the settings of the rear air conditioning. The information is provided in form of the text and symbols.
Vehicle Climate Control - Troubleshooting-Function-Design-Operation - Current Passenger Car Models b
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2.1/4
Model 221.095/195 (S-Class Hybrid)
Climate control operation
Model 221.095/195 (S-Class Hybrid)
Climate control operation
Center outlets
17 18 19 20 Left center air outlet Left center air outlet adjustment wheel Right center air outlet adjustment wheel Right center air outlet
P83.40-3529-00
Control options
Center air outlets (17, 20) Turning the left center air outlet adjustment wheel (18) and the right center air outlet adjustment wheel (19) regulates the emerging air flow. If the left center air outlet adjustment wheel (18) or the right center air outlet adjustment wheel (19) is turned all the way up, the left center air outlet (17) or the right center air outlet (20) is fully opened. The flow direction of the air can be adjusted by moving the respective slide control on the left center air outlet (17) and the right center air outlet (20). Move the respective slide control of the left center air outlet (17) and the right center air outlet (20) to the center position for draft-free ventilation. Setting ventilation modes via the COMAND controller unit (A40/3) The air flow can also be adjusted separately in the COMAND controller unit (A40/3) via the climate control menu. The ventilation modes "Diffuse", "Medium" and "Focussed" can be selected. This allows the air flow and air distribution of the air conditioning in automatic mode to be adjusted more precisely. • "Diffuse" air flow: The air flow is kept low and is not directed at the occupants if possible. • "Medium" air flow: The air flow is approximately the same as in the standard setting of automatic mode. • "Focussed" air flow: The air flow is kept higher.
2.1/5
b Vehicle Climate Control - Troubleshooting-Function-Design-Operation - Current Passenger Car Models
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Shown on model 221 with code 581, 582/for legend see from 3.1/4
Vehicle Climate Control - Troubleshooting-Function-Design-Operation - Current Passenger Car Models b
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3.1/1
Model 221.095/195 (S-Class Hybrid)
Climate control system overview
P83.40-4566-00
Model 221.095/195 (S-Class Hybrid)
Climate control system overview
P83.40-4567-00
3.1/2
b Vehicle Climate Control - Troubleshooting-Function-Design-Operation - Current Passenger Car Models
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Shown with code 581/for legend see from 3.1/4
Shown with code 581, 582/for legend see from 3.1/4
Vehicle Climate Control - Troubleshooting-Function-Design-Operation - Current Passenger Car Models b
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3.1/3
Model 221.095/195 (S-Class Hybrid)
Climate control system overview
P83.40-4568-00
Model 221.095/195 (S-Class Hybrid)
30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 A1 A8/1 A9/5 A31/1 A32m1 A32n1 A40/3 A40/8 A40/9 A40/10 A85s1 A85/1s1 A85/3s1 A85/4s1 A98 A100 A100b2 B10/4 B10/6 B10/9 B10/10 B10/11 B10/31 B10/32 B10/35 B10/36 B11/4 B12 B14 B31/1 B32/2 CAN A CAN B CAN E CAN F CAN I KB LIN B8 LVDS Telematics CAN Interior CAN Vehicle CAN Central CAN Drivetrain sensor CAN AC bus Climate control LIN Low voltage differential signal Instrument cluster Transmitter key Electric refrigerant compressor Rear auxiliary heating system delivery unit Blower motor Blower regulator COMAND control unit COMAND display Front central operating unit SPLITVIEW display Left front rotary tumbler switch Right front rotary tumbler switch Left rear rotary tumbler switch Right rear rotary tumbler switch Panoramic sliding sunroof control module High-voltage battery module High-voltage battery cell temperature sensors In-car temperature sensor Evaporator temperature sensor Left rear air conditioning heat exchanger temperature sensor Right rear air conditioning heat exchanger temperature sensor Rear air conditioning evaporator temperature sensor Left side outlet temperature sensor Right side outlet temperature sensor Left footwell temperature sensor Right footwell temperature sensor Coolant temperature sensor Refrigerant pressure sensor Outside temperature display temperature sensor AAC [KLA] multifunction sensor AAC [KLA] sun sensor (4 in total) Blower motor actuation Actuation of refrigerant shutoff valve Refrigerant compressor request Heater circulation pump request Actuation of heater circulation pump Idle speed increase request Electric radiator fan request Electric radiator fan actuation Actuation of air flap actuator motors Rear air conditioning settings status Rear blower motor request Rear blower motor actuation Air conditioning water valve request Air conditioning water valve actuation Actuation of rear water pump with pulsed valve COMAND display request High-voltage battery cooling shutoff valve request High-voltage battery cooling shutoff valve actuation
3.1/4
Climate control system overview
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29
Battery voltage/circuit status Vehicle speed signal Window position Air outlet temperature Dew point temperature and pollutant concentration Outside temperature Refrigerant pressure Interior temperature Evaporator temperature Charge indicator lamp signal Solar radiation Coolant temperature Engine speed Rear air conditioning remote control Rear air conditioning evaporator temperature Upper control panel control unit request Door status Position of air outlets selector wheel Rear air conditioning heat exchanger temperature Front central operating unit request COMAND display actuation Refrigerant compressor status Battery cooling request Evaporator drying request Voice input Tilting/sliding roof position Panoramic sliding sunroof motor actuation Temperature of high-voltage battery cells Blower motor request
b Vehicle Climate Control - Troubleshooting-Function-Design-Operation - Current Passenger Car Models
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M2/1 M2/5 N3/10 N10/1 N22/1 N22/4 N29/2 N69/1 N69/2 N69/3 N69/4 N70 N72/1 N73 N82/2 N93 R41/1 R41/2 R41/3r1 R41/3r2 R41/4r1 R41/4r2 Y19/1 Y19/2 Y67 Left side air outlet potentiometer Right side air outlet potentiometer Left front center air outlet potentiometer Right front center air outlet potentiometer Left rear center air outlet potentiometer Right rear center air outlet potentiometer High-voltage battery cooling shutoff valve Air conditioner water valve Rear AC refrigerant shutoff valve ME-SFI [ME] control unit Front SAM control unit with fuse and relay module AAC [KLA] control unit Rear air conditioning control unit Rear air conditioning electronic blower regulator Left front door control unit Right front door control unit Left rear door control unit Right rear door control unit Overhead control panel control unit Upper control panel control unit EZS control unit Battery management system control unit Central gateway control unit
M2/8 M2/9 M2/10 M2/11 M2/12 M2/13 M2/17 M2/18 M2/30 M2/31 M2/32 M2/33 M4/7
M13 M16/19 M16/20 M16/33 M16/34
Rear blower motor Fresh air/air recirculation flaps actuator motor Left defroster vent flap actuator motor Right defroster vent flap actuator motor Left footwell flap actuator motor Right footwell flap actuator motor Left center air flap actuator motor Right center air flap actuator motor Left side outlet flap actuator motor Right side outlet flap actuator motor Upper left blend air flap actuator motor Lower left blend air flap actuator motor Upper right blend air flap actuator motor Lower right blend air flap actuator motor Engine and air conditioning electric suction fan with integrated control Heater circulation pump Left rear center air outlet actuator motor Right rear center air outlet actuator motor Left B-pillar air distribution actuator motor Right B-pillar air distribution actuator motor
Vehicle Climate Control - Troubleshooting-Function-Design-Operation - Current Passenger Car Models b
i Note
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3.1/5
Model 221.095/195 (S-Class Hybrid)
Climate control system overview
The system overview, data flow and block diagrams are shown on a vehicle with the full equipment (with codes 581, 582). The differences in the components in the various equipment packages (code 581, 582) are shown in the overview of components.
Model 221.095/195 (S-Class Hybrid)
Components in general
Rear heating system delivery unit (A31/1) (code 582)
Location: The rear heating system delivery unit (A31/1) is located in the right front wheel well behind the wheel well liner. It consists of two duovalves and one heater circulation pump. Task: It provides support when the engine is running and, when residual heat mode is switched on, it pumps the engine coolant through the heater heat exchanger of the rear air conditioning. Failure: No heat output in residual heat mode.
P83.40-3195-00
Blower motor (A32m1)/blower regulator (A32n1)
Location: The blower motor (A32m1) and the blower regulator (A32n1) are located under the glove compartment on the air conditioner housing. Task of blower motor:The blower motor (A32m1) delivers fresh or interior air through the air conditioner housing into the vehicle interior. Task of blower regulator: The blower regulator (A32n1) controls the voltage supply of the blower motor (A32m1) in relation to the air flow requested by the AAC control unit (N22/1). Blower motor failure: No fresh or interior air is delivered to the vehicle interior. Failure of blower regulator: The blower motor (A32m1) is actuated at 50% via a limp-home function.
P83.40-3196-00
4.1/1
b Vehicle Climate Control - Troubleshooting-Function-Design-Operation - Current Passenger Car Models
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In-car temperature sensor (B10/4)
Location: The in-car temperature sensor (B10/4) is located on the left above the EZS control unit (N73). Task: It records the temperature in the lower area of the vehicle interior. Failure: Exact regulation of the interior temperature is not possible.
P83.40-3177-00
Side outlet temperature sensors (B10/31, B10/32)/footwell temperature sensors (B10/35, B10/36)
Location: The side outlet temperature sensors, left (B10/31) and right (B10/32), and the footwell temperature sensors, left (B10/35) and right (B10/36), are located in the air conditioner housing behind the relevant air flap. Task: They register the temperature of the air emerging at the relevant air flap. Failure: Exact temperature control of the air emerging from the front air conditioner housing is not possible.
P83.40-3182-00
Coolant temperature sensor (B11/4)
Location: The coolant temperature sensor (B11/4) is located towards the rear on the left cylinder head in vehicles with engine 272, for example. Task: It registers the temperature of the engine coolant and transmits it to the ME-SFI [ME] control unit (N3/10). Failure: Refrigerant compressor (A9) operation is limited. The engine and air conditioning electric suction fan with integrated control (M4/7) is fully actuated.
P83.40-3184-00
Vehicle Climate Control - Troubleshooting-Function-Design-Operation - Current Passenger Car Models b
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4.1/2
Model 221.095/195 (S-Class Hybrid)
Components in general
Model 221.095/195 (S-Class Hybrid)
Components in general
Outside temperature display temperature sensor (B14)
Location: The outside temperature display temperature sensor (B14) is located at the front on the left in the bumper. Task: It registers the outside air temperature. Failure: The air conditioning continues to operate with the most recent stored value from the outside temperature display temperature sensor (B14). The air conditioning system no longer adjusts the temperature correctly to cater for changing conditions.
P83.40-3186-00
AAC [KLA] multifunction sensor (B31/1)
Location: The AAC [KLA] multifunction sensor (B31/1) is located behind the high-voltage battery module (A100) in the rear of the engine compartment on the right. Task: It registers the dew point temperature and the concentration of the pollutants carbon monoxide and nitrogen oxide in the air flow of the incoming outside air. Failure: The air conditioning is regulated by means of a substitute characteristic. Exact regulation of the air humidity is therefore not possible. In addition, automatic switchover to air recirculation mode is not possible.
P83.10-2800-00
AAC [KLA] sun sensor (4 in total) (B32/2)
Location: The AAC [KLA] sun sensor (4 in total) (B32/2) is located in the left air inlet in the engine hood. Task: It is a 4-zone sensor that determines the intensity and the incidence angle of the solar radiation on the vehicle in four separate areas (left front, right front, left rear and right rear). Failure: Automatic adjustment of the interior climate control via solar intensity and incidence angle is not possible.
P83.40-3188-00
4.1/3
b Vehicle Climate Control - Troubleshooting-Function-Design-Operation - Current Passenger Car Models
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Rear blower motor (M2/1)/rear air conditioning electronic blower regulator (N29/2) with code 582
Location: The rear blower motor (M2/1) and the rear air conditioning electronic blower regulator (N29/2) are located under the center console in the rear air conditioner housing. Task of blower motor: The rear blower motor (M2/1) delivers interior air to the rear area of the vehicle interior via the rear center outlets. When the rear air conditioning control unit (N22/4) is in automatic mode, the rear blower motor (M2/1) is only actuated in cooling mode. Task of blower regulator: The rear air conditioning electronic blower regulator (N29/2) controls the voltage supply of the rear blower motor (M2/1) in relation to the air flow requested by the AAC [KLA] control unit (N22/1) or the rear air conditioning control unit (N22/4). Blower motor failure: No interior air is delivered to the rear of the vehicle interior. Failure of blower regulator: The rear blower motor (M2/1) is not actuated.
P83.40-3197-00
Vehicle Climate Control - Troubleshooting-Function-Design-Operation - Current Passenger Car Models b
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4.1/4
Model 221.095/195 (S-Class Hybrid)
Components in general
Model 221.095/195 (S-Class Hybrid)
Components in general
Front air conditioner housing air flap actuator motors (M2/5, M2/8, M2/9, M2/10, M2/11, M2/12, M2/13, M2/17, M2/18, M2/30, M2/31, M2/32, M2/33)
Location: The actuator motors for the fresh air/air recirculation flaps (M2/5), for the defroster flaps, left (M2/8) and right (M2/9), for the footwell flaps, left (M2/10) and right (M2/11), for the center air outlet air flaps, left (M2/12) and right (M2/13), for the side air outlet flaps, left (M2/17) and right (M2/18), and for the blend air flaps, upper left (M2/30), lower left (M2/31), upper right (M2/32) and lower right (M2/33), are located on the front air conditioner housing. Task: By appropriately adjusting the air direction and blend air flaps in the air conditioner housing, the actuator motors regulate the temperature and air distribution in the vehicle interior. The fresh air/ air recirculation flaps actuator motor (M2/5) regulates the supply of fresh or recirculated air. Failure: The actuator motors are actuated via a LIN bus. If an actuator motor fails, all the other actuator motors downstream of it shut down or switch to limp-home mode (the sequence is illustrated in the block diagram). The air emerges from the affected air outlet either all the time or never, depending on the position of the actuator motor. If the fresh air/ air recirculation flaps actuator motor (M2/5) fails, adjustment of the fresh and air recirculation flaps is no longer possible. If one of the blend air flap actuator motors (M2/30, M2/31, M2/32, M2/33) fails, the temperature of the air emerging from the air conditioner housing can no longer be regulated. In limp-home mode heated fresh air is directed to the windows in order to prevent them from fogging. The actuator motors for the fresh air/air recirculation flap (M2/5), for the blend air flaps, upper left (M2/30), lower left (M2/31), upper right (M2/ 32) and lower right (M2/33), and for the defroster flaps, left (M2/8) and right (M2/9), open the corresponding flaps.
P83.40-3198-00
P83.40-3200-00
The actuator motors for the footwell flaps, left (M2/10) and right (M2/11), for the center air outlet air flaps, left (M2/12) and right (M2/13), and for the side air outlet flaps, left (M2/17) and right (M2/18), close the corresponding flaps.
4.1/5
b Vehicle Climate Control - Troubleshooting-Function-Design-Operation - Current Passenger Car Models
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Engine and air conditioning electric suction fan with integrated control (M4/7)
Location: The engine and air conditioning electric suction fan with integrated control (M4/7) is located behind the radiators. Task: It draws in air through the radiators in order to cool the engine coolant and the refrigerant of the air conditioning system. Failure: The refrigerant compressor (A9) may be shut off depending on the ambient conditions and the engine variant.
P83.40-3202-00
Heater circulation pump (M13)
Location: The heater circulation pump (M13) is located at the rear of the engine compartment on the left beside the brake booster. Task: It provides support when the engine is running and, when residual heat mode is switched on, it pumps the engine coolant through the heater heat exchanger. Failure: No heat output in residual heat mode.
P83.40-3203-00
Rear center air outlet actuator motor, left (M16/19)/right (M16/20) with code 582
Location: The rear center air outlet actuator motors, left (M16/19) and right (M16/20), are located on the rear air conditioner housing. Task: By appropriately adjusting the air direction flaps in the air conditioner housing, the actuator motors regulate the air distribution in the vehicle interior. Failure: The air emerges from the affected air outlet either all the time or never, depending on the position of the actuator motor.
P83.40-3199-00
Vehicle Climate Control - Troubleshooting-Function-Design-Operation - Current Passenger Car Models b
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4.1/6
Model 221.095/195 (S-Class Hybrid)
Components in general
Model 221.095/195 (S-Class Hybrid)
Components in general
B-pillar air distribution actuator motors, left (M16/33)/right (M16/34)
Location: The B-pillar air distribution actuator motors, left (M16/33) and right (M16/34), are embedded in the air distribution ducts in the floor covering under the front seats. Task: They serve to adjust the air flaps in the air distribution ducts. Failure: The air emerges from the affected air outlet either all the time or never, depending on the position of the actuator motor.
P83.40-3204-00
AAC [KLA] control unit (N22/1)
Location: The AAC [KLA] control unit (N22/1) is located on the front of the air conditioner housing on the passenger side. Task: It controls and regulates all interior climate control functions, the electric refrigerant compressor (A9/5), the climate control functions of the stationary heater (with code 228) and the remote control for the rear automatic air conditioning (with code 582). Failure: The electric refrigerant compressor (A9/5) can no longer be actuated, all climate control functions can fail.
P83.40-4569-00
4.1/7
b Vehicle Climate Control - Troubleshooting-Function-Design-Operation - Current Passenger Car Models
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Air conditioner water valve (Y19/2)
Location: The air conditioner water valve (Y19/2) is located below the windshield wiper mechanism. Task: It continuously regulates the flow of temperature-controlled engine coolant to the heater heat exchanger. Failure: No or low heat output from air conditioning.
P83.40-3206-00
Coolant thermostat
Location: The coolant thermostat is located on the cylinder head. Task: The coolant thermostat steplessly switches between the small and large coolant circuit to ensure that the engine rapidly reaches its operating temperature and maintains this temperature during operation with as little fluctuation as possible. Failure: Lower or delayed heat output or engine overheating.
P83.20-2351-00
Vehicle Climate Control - Troubleshooting-Function-Design-Operation - Current Passenger Car Models b
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4.1/8
Model 221.095/195 (S-Class Hybrid)
Components in general
Model 221.095/195 (S-Class Hybrid)
R134a components
Electric refrigerant compressor (A9/5)
Location: The electric refrigerant compressor (A9/5) is located at the lower left of the engine. Task: It is responsible for taking in and compressing the refrigerant. In order to provide adequate cooling output even when the engine has been automatically stopped, the drive system for the refrigerant compressor has to be separated from the combustion engine to provide independent climate control for the vehicle interior and independent cooling for the highvoltage battery. Depending on the evaporator temperature, the electric refrigerant compressor is steplessly regulated by the AAC [KLA] control unit (N22/1) from 700 to 9000 rpm. Power is supplied via the highvoltage battery module. Failure: Loss of cooling output. This means that the vehicle interior and high-voltage battery module (A100) cannot be adequately cooled. If the high-voltage battery module (A100) overheats, the high-voltage electric circuit is interrupted. All hybrid functions (boost and regenerative braking) are then no longer active.
P83.55-2201-00
Electric refrigerant compressor (A9/5) 1 Control unit 2 Spiral compressor 3 Electric motor
P83.55-2202-00
i Note The familiar R134a refrigerant compressor oil is used for refrigerant compressor oil.
i Note The first time the electric refrigerant compressor (A9/5) is started, the engine must be running. After this, cooling is possible even without engine operation (stop mode).
4.2.1/1
b Vehicle Climate Control - Troubleshooting-Function-Design-Operation - Current Passenger Car Models
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High-voltage battery module (A100)/battery management system control unit (N82/2)
Location: The high-voltage battery module (A100) is located at the right rear of the engine compartment. The battery management system control unit (N82/2) is integrated into the high voltage battery module. Task of high-voltage battery module: The highvoltage battery module (A100) protects the highvoltage battery from external heat and provides mechanical stability. The high-voltage battery stores electrical energy and supplies all high voltage system components with 126 V. The most important high voltage system components are: • Integrated starter alternator (A79) • Electric refrigerant compressor (A9/5) Task of battery management system control unit: The battery management system control unit (N82/2) performs battery management as part of an electrical network with the sensors and actuators of the high-voltage system. The battery management system constantly determines and monitors the following high voltage battery data: • • • • High voltage interlock Voltage, current flow Temperature Status of protection switches (5)
P54.10-3569-00
High-voltage battery module (A100) 1 2 3 4 5 A100 A100g1 N82/2
Plug connection for battery management system control unit Refrigerant line connection High-voltage plug connection Service Disconnect switch plug connection Protection switch High-voltage battery module High-voltage battery Battery management system control unit
Failure: The high-voltage electric circuit is interrupted. All hybrid functions (boost and regenerative braking) and operation of the electric refrigerant compressor (A9/5) are then no longer possible.
i Note If the high-voltage battery still requires cooling, the air conditioning cannot be shut off (disable function: the deactivation is reversed after 2 s). The air conditioning remains switched on after the battery is cooled.
Vehicle Climate Control - Troubleshooting-Function-Design-Operation - Current Passenger Car Models b
– This printout will not be recorded by the update service. Status: 01 / 2011 –
4.2.1/2
Model 221.095/195 (S-Class Hybrid)
R134a components
Model 221.095/195 (S-Class Hybrid)
R134a components
Evaporator temperature sensor (B10/6)
Location: The evaporator temperature sensor (B10/6) is located on the left on the air conditioner housing in the air flow downstream of the evaporator. Task: It registers the temperature of the air flow emerging from the evaporator. Failure: The electric refrigerant compressor (A9/5) is shut off.
P83.40-3178-00
Rear air conditioning heat exchanger temperature sensor, left (B10/9)/right (B10/10) (Code 582)
Location: The rear air conditioning heat exchanger temperature sensors, left (B10/9) and right (B10/10), are located on each side of the rear air conditioner housing. Task: They register the temperature of the heated air downstream of the heater heat exchanger. Failure: Exact temperature control of the air emerging from the rear air conditioner housing is not possible.
P83.40-3179-00
Rear air conditioning evaporator temperature sensor (B10/11) (code 582)
Location: The rear air conditioning evaporator temperature sensor (B10/11) is located on the side of the rear air conditioner housing in the air flow downstream of the evaporator. Task: It registers the temperature of the air flow emerging from the rear air conditioner housing evaporator. Failure: Refrigerant feed to the rear air conditioning is interrupted. The front air conditioning system continues to operate with no functional limitations.
P83.40-3181-00
4.2.1/3
b Vehicle Climate Control - Troubleshooting-Function-Design-Operation - Current Passenger Car Models
– This printout will not be recorded by the update service. Status: 01 / 2011 –
Refrigerant pressure sensor (B12)
Location: The refrigerant pressure sensor (B12) is located in the left front wheel well behind the wheel well liner. Task: It registers the refrigerant pressure in the high pressure circuit of the air conditioning system. Failure: The electric refrigerant compressor (A9/5) is shut off.
P83.40-3185-00
High-voltage battery cooling shutoff valve (Y19/1)
Location: The high-voltage battery cooling shutoff valve (Y19/1) is located in the radiator tank. Task: The high-voltage battery cooling shutoff valve (Y19/1) is actuated by the battery management system control unit (N82/2) and regulates the flow of refrigerant to the high-voltage battery. Failure: The high-voltage battery and the control unit cannot be temperature-controlled and are disabled if they overheat.
P83.40-4570-00
Vehicle Climate Control - Troubleshooting-Function-Design-Operation - Current Passenger Car Models b
– This printout will not be recorded by the update service. Status: 01 / 2011 –
4.2.1/4
Model 221.095/195 (S-Class Hybrid)
R134a components
Model 221.095/195 (S-Class Hybrid)
R134a components
Rear AC refrigerant shutoff valve (Y67) (code 582)
Location: The rear air conditioning refrigerant shutoff valve (Y67) with integrated throttle is located in the left front wheel well behind the wheel well liner. Task: The rear AC refrigerant shutoff valve (Y67) controls the flow of refrigerant in the air conditioning system to the evaporator of the rear air conditioning. The throttle performs the function of an expansion valve. Fail: Loss of cooling output of rear air conditioning due to interruption of refrigerant circuit.
P83.40-3207-00
Expansion valve
Location: The expansion valve (1) is located at the center of the water trough below the windshield wiper mechanism. Task: The expansion valve (1) sprays liquid refrigerant into the evaporator. The injection quantity depends on the pressure and temperature of the refrigerant supplied. Failure: The required cooling output is not achieved or the high pressure increases above the specified value.
P83.40-3689-00
Fluid reservoir
Location: The fluid reservoir (2) is located at left front in the rear area of the wheel well. Task: In the fluid reservoir (2), the refrigerant is cleaned of chemical and mechanical contamination. Failure: Refrigerant compressor defect (A9) due to contaminated refrigerant circuit.
P83.40-3699-00
4.2.1/5
b Vehicle Climate Control - Troubleshooting-Function-Design-Operation - Current Passenger Car Models
– This printout will not be recorded by the update service. Status: 01 / 2011 –
Continued upon the introduction of new model series
Vehicle Climate Control - Troubleshooting-Function-Design-Operation - Current Passenger Car Models b
– This printout will not be recorded by the update service. Status: 01 / 2011 –