FRONT A/C DISPLAY CONTROL HEAD, Climatronic Control Module - J255-, A/C SYSTEM CONTROL AND REGULATION

The front Air Conditioning (A/C) display control heads, the Climatronic Control Module -J255-, cannot currently be interchanged as usual; the component protection is in effect. The component protection (anti-theft protection) can only be canceled by entering specific vehicle data, refer to Vehicle Diagnostic Tester in "Guided Fault Finding  " Function.

If a Climatronic Control Module -J255- with active component protection (anti-theft system) is installed in a different vehicle, only the functions necessary for vehicle safety can be selected. Comfort functions cannot be selected, refer to Vehicle Diagnostic Tester in the "Guided Fault Finding  " function.

Pay attention to precise allocation when replacing a Climatronic Control Module -J255-. There are different versions for vehicles with or without a button for seat heating and/or seat ventilation, etc .

Pressing the buttons of the Climatronic Control Module -J255- or the Rear A/C Display Control Head -E265- for an extended period of time (for example due to an object lying on them) can cause a fault to be stored in the event memory indicating that the buttons are stuck. If necessary, check the function of the buttons and erase the event memory if no malfunction is found.

The seat heating and seat ventilation setting is set on the Climatronic Control Module -J255-. This setting is transmitted via the data bus, for example, to the Vehicle Electrical System Control Module -J519-. The target temperatures for the different seat heating and seat ventilation settings are stored in the Vehicle Electrical System Control Module -J519-. Depending on the version of the Vehicle Electrical System Control Module -J519- and the vehicle production period, the target temperature for the seat heating and seat ventilation can differ with the same setting on the Climatronic Control Module -J255-, refer to SEAT HEATING  and Vehicle Diagnostic Tester in the "Guided Fault Finding  " function (for the Vehicle Electrical System Control Module -J519-).

If a new Climatronic Control Module -J255- was installed and the basic setting was not performed, the A/C system control is limited and this is displayed in the event memory as a malfunction. Therefore, perform the basic setting for the A/C system after installation of the Climatronic Control Module -J255- according to specification, refer to Vehicle Diagnostic Tester in the "Guided Fault Finding  " function.

The buttons, the display, and the rotary switch of the Climatronic Control Module -J255- are illuminated by LEDs (LEDs cannot be replaced).

The function indicator lamps in the buttons and in the rotary switches of the Climatronic Control Module -J255- cannot be replaced separately.

In the case of an incorrect measurement of the infrared sensor for temperature and sunlight installed in the Climatronic Control Module -J255-, check the trim of the Climatronic Control Module -J255-. The infrared sensor for temperature and sunlight may not be taped over or covered, refer to Vehicle Diagnostic Tester in "Guided Fault Finding  " function.

The selected functions are displayed by illumination of function indicator lamps in the various buttons and rotary switches or in the display fields of the Climatronic Control Module -J255-.

Depending on the version and the setting of the Climatronic Control Module -J255-, the currently selected functions are shown in the display of the Climatronic Control Module -J255- and on the Multi Media Interface (MMI) display or only on the display of the Climatronic Control Module -J255-. The duration of the display on the MMI display can be set via the "adaptation" function in the "Guided Fault Finding  " of the Climatronic Control Module -J255- see Vehicle Diagnostic Tester in the "Guided Fault Finding  " function.

If no malfunction is stored but a function of the Climatronic Control Module -J255- is not available, check the adaptation of the Climatronic Control Module -J255- (the function may be switched off by a setting). If necessary, reset the adaptations in all adaptation channels to the manufacturer setting, refer to Vehicle Diagnostic Tester in the "Guided Fault Finding  " function.

If there is a condition, where the heating or ventilation of the driver of passenger seat cannot be switched on, this will be stored as a malfunction in the Vehicle Electrical System Control Module -J519-, in the Memory Seat/Steering Column Adjustment Control Module -J136- or in Front Passenger Memory Seat Control Module -J521- (depending on the vehicle type and the vehicle equipment level). In this vehicle, information stating that the event memory in the relevant control module or in the Comfort System Central Control Module -J393- needs to be read out is currently not sent via the data bus to the front A/C display control module, the Climatronic Control Module -J255- see Vehicle Diagnostic Tester in the "Guided Fault Finding  " function. In the event of a complaint regarding seat heating or seat ventilation, first check the event memory of the control modules activating the seat heating and seat ventilation.

This vehicle has a start-stop system for specific engines as optional equipment. In vehicles with a start-stop system, the stop function is prevented depending on the setting of the front A/C display control head, the Climatronic Control Module -J255-. If, for example, "defrost" is selected, the stop function is not possible or will be interrupted and the engine will start. The same applies in the case of heating and cooling. The difference between the target and actual temperature is greater than a specified value, refer to Vehicle Diagnostic Tester in the "Guided Fault Finding  " function.

Certain A/C system functions can be switched on and off via the MMI (Multi Media Interface) under the "A/C system" function in the "car" / "car systems" menu. The A/C system control can also be influenced via presettings in the MMI under the "A/C system" function in the "car" / "car systems" menu. Therefore, first check the presetting in the MMI in the case of a problem with these components, refer to Infotainment/MMI Operating Instructions.

Starting with a gradual introduction in MY 2014 (exact launch date TBD), the new Climatronic Control Module -J255- A/C display control heads will come into use (different functions, with part number up to index "H" recognizable, for example, by button AC  and with part number from index "J" recognizable, for example, by button A/C  ) .

Vehicles with a high voltage system are only offered with a rear air distribution housing for the A/C system (without rear A/C unit).

The Climatronic Control Module -J255- is installed in vehicles with a high voltage system at the start of production, for example with part number 4G0 820 043 and the "F", "G" and "H" indexes .