Climatronic Control Module -J255-, GENERAL INFORMATION: Notes

Certain A/C system functions can be switched on and off via the MMI (Multi Media Interface) under the "Air Conditioning (A/C) system" function in the "car" / "car systems" menu. The A/C system control can also be influenced via pre-settings in the MMI (Multi Media Interface) 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.
With the Start/Stop Function, the stop function is disabled depending on the setting on the Climatronic Control Module -J255- control head. If, for example, "Defrost" mode is selected, the stop function is not possible or is cancelled and the engine is started as soon as this mode is selected. The same applies in the case of heating and cooling. The difference between the target and actual temperature is greater than a specified value. Use the Vehicle Diagnostic Tester in the "Guided Fault Finding" function.
The Climatronic Control Module -J255- control heads currently can be interchanged; the component protection is not 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 an 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 can no longer be selected.
The buttons and knobs are illuminated with LEDs, they cannot be replaced individually
The function indicator lamps in the buttons and knobs cannot be replaced separately.
Pressing the buttons for the Climatronic Control Module -J255- control head 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 ventilation setting is adjusted with the Climatronic Control Module -J255- control head. The setting is transmitted to the Vehicle Electrical System Control Module -J519- via the data bus. 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-, the specified temperature for the seat heating and ventilation can be different with the same setting on the Climatronic Control Module -J255- control head. Use the Vehicle Diagnostic Tester in "Guided Fault Finding" Function (for the Vehicle Electrical System Control Module -J519-).
Check the temperature and sunshine infrared sensor for a faulty measurement in the Climatronic Control Module -J255- control head. The infrared sensor for temperature and sunlight may not be taped over or covered. Use the Vehicle Diagnostic Tester in the "Guided Fault Finding" function.
The selected functions are displayed when the LEDs in the various Climatronic Control Module -J255- control head buttons and knobs illuminate.
For vehicles in the "Basic" version there is no display for the currently selected functions for the Climatronic Control Module -J255- control head in the display for the MMI display. Only specific adjustments are displayed. Refer to Vehicle Diagnostic Tester. The length of time for the display can be adjusted using the "Adaption" function for the Climatronic Control Module -J255- control head. Use the Vehicle Diagnostic Tester in "Guided Fault Finding" function.
For vehicles in the "Comfort" version, the currently selected functions will appear in the display for the Climatronic Control Module -J255- control head and in the display for the MMI display. The length of time for the display can be adjusted using the "Adaptation" function for the Climatronic Control Module -J255- control head. Use the Vehicle Diagnostic Tester in "Guided Fault Finding" function.
If no malfunction is stored and a function is not available, check the adaptation of the Climatronic Control Module -J255- (the function may be switched off by a setting). If the adaptation resets to the manufacturer adjustments in all of the adaptation channels. Refer to Vehicle Diagnostic Tester in "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 the Front Passenger Memory Seat Control Module -J521-. Currently for this vehicle information is not always sent to the Climatronic Control Module -J255- control head via the data bus. Use the Vehicle Diagnostic Tester in "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. Use the Vehicle Diagnostic Tester in "Guided Fault Finding" function.
If a new Climatronic Control Module -J255- control head was installed and the basic setting was not performed, A/C regulation is limited and a malfunction concerning this is stored in the Diagnostic Trouble Code (DTC) memory. Use the Vehicle Diagnostic Tester in "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 pre-settings in the MMI (Multi Media Interface) 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.
With the Start/Stop Function, the stop function is disabled depending on the setting on the Climatronic Control Module -J255- control head. If, for example, "Defrost" mode is selected, the stop function is not possible or is cancelled and the engine is started as soon as this mode is selected. The same applies in the case of heating and cooling. The difference between the target and actual temperature is greater than a specified value. Use the Vehicle Diagnostic Tester in "Guided Fault Finding" function.
The Climatronic Control Module -J255- control heads currently can be interchanged; the component protection is not 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 an 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 can no longer be selected.
The buttons and knobs are illuminated with LEDs, they cannot be replaced individually
The function indicator lamps in the buttons and knobs cannot be replaced separately.
Pressing the buttons for the Climatronic Control Module -J255- control head 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 ventilation setting is adjusted with the Climatronic Control Module -J255- control head. The setting is transmitted to the Vehicle Electrical System Control Module -J519- via the data bus. 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-, the specified temperature for the seat heating and ventilation can be different with the same setting on the Climatronic Control Module -J255- control head. Refer to Vehicle Diagnostic Tester in "Guided Fault Finding" function (for the Vehicle Electrical System Control Module -J519-).
Check the temperature and sunshine infrared sensor for a faulty measurement in the Climatronic Control Module -J255- control head. 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 when the LEDs in the various Climatronic Control Module -J255- control head buttons and knobs illuminate.
For vehicles in the "Basic" version there is no display for the currently selected functions for the Climatronic Control Module -J255- control head in the display for the MMI display. Only specific adjustments are displayed. Refer to Vehicle Operating Instructions. The length of time for the display can be adjusted using the "Adaptation" function for the Climatronic Control Module -J255- control head. Use the Vehicle Diagnostic Tester in "Guided Fault Finding" function.
For vehicles in the "Comfort" version, the currently selected functions will appear in the display for the Climatronic Control Module -J255- control head and in the display for the MMI display. The length of time for the display can be adjusted using the "Adaption" function for the Climatronic Control Module -J255- control head. Use the Vehicle Diagnostic Tester in "Guided Fault Finding" function.
If no malfunction is stored and a function 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 "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 the Front Passenger Memory Seat Control Module -J521-. Currently for this vehicle information is not always sent to the Climatronic Control Module -J255- control head via the data bus. Use the Vehicle Diagnostic Tester in "Guided Fault Finding" function.
In the event of a complaint regarding seat heating or ventilation, first check the event memory of the control modules activating the seat heating and ventilation. Use the Vehicle Diagnostic Tester in "Guided Fault Finding" function.
If a new Climatronic Control Module -J255- control head was installed and the basic setting was not performed, A/C regulation is limited and a malfunction concerning this is stored in the Diagnostic Trouble Code (DTC) memory. Use the Vehicle Diagnostic Tester in "Guided Fault Finding" function.
Starting in MY 2013, the air distribution display in the MMI display will change. As well, a new Climatronic Control Module -J255- control head will be installed (Climatronic Control Module -J255- with part number 4G0 820 043 starting with index "AA"). Observe the correct allocation.
The Comfort System Central Control Module -J393- evaluates signals from Humidity Sensor -G355- in vehicles through MY 2012. Starting with MY 2013 vehicles, the Vehicle Electrical System Control Module -J519- will evaluate the signal from the Humidity Sensor -G355- and transmit the measured value to the Climatronic Control Module -J255- control head. Observe the correct implementation and allocation of the Climatronic Control Module -J255-. Use the Vehicle Diagnostic Tester in "Guided Fault Finding" function and to the appropriate wiring diagram
Depending on time period of production (from MY 2013 as a running change) and vehicle version, the Humidity Sensor -G355- no longer operates as an individual part in the DTC memory. On these vehicles, the Rain/Light Recognition Sensor -G397- is displayed as the fault location in the event of a deviation on the Humidity Sensor -G355-.
On vehicles with a "Basis" A/C system, the left and right instrument panel vents are installed without the position sensors (Position Sensor In Left Side Vent -G628- and Position Sensor In Right Side Vent -G629-) by the manufacturer. However, instrument panel vents with a position sensor may retroactively be installed together with the corresponding cables and a special "Basis" version of the Climatronic Control Module -J255- (with an additional connector -5-) in individual vehicles. The connectors between the Climatronic Control Module -J255- and the two position sensors (at the Position Sensor In Left Side Vent -G628- and Position Sensor In Right Side Vent -G629-) correspond largely to the installed connections by the manufacturer on the "Comfort" version. Refer to the appropriate wiring diagram The retroactive installation is recorded in the vehicle history (repair history) for this vehicle.

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