Control Module HVAC: Description and Operation

Climatronic Control Module (J255)

• 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 (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.

• The Climatronic control module, currently cannot be interchanged; component protection is in effect. Component protection (anti-theft protection) can only be canceled by entering specific vehicle data using the Vehicle Diagnostic Tester in the "Guided Fault Finding" function.

• If a Climatronic control module 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 rotatory knobs are illuminated with LEDs, they cannot be replaced individually

• The function feedback lamps in the buttons and rotary knobs cannot be replaced separately.

• Pressing the buttons on the Climatronic control module, for an extended period of time, for example if an object is 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 on the Climatronic control module. This 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. Depending on the version of the Vehicle electrical system control module, the target temperature for seat heating and seat ventilation can therefore differ with the same setting on the Climatronic control module. Refer to=> [ Seat Heating and Ventilation, Checking ] Seat Heating and Ventilation, Checking and Vehicle Diagnostic Tester in the"Guided Fault Finding" function (for the Vehicle electrical system control module).

• Check in the case of an incorrect measurement of the infrared sensor for temperature and solar radiation installed in the Climatronic control module. The infrared sensor for temperature and solar radiation may not be taped over or covered. Check using the Vehicle Diagnostic Tester in the "Guided Fault Finding" function.

• The selected functions are indicated by illuminated LEDs in the various buttons and knobs of the Climatronic control module.

• In the case of Basic vehicles, the currently selected functions are not displayed by the Climatronic control module on the Multi Media Interface (MMI) display. Only certain settings are displayed. Refer to the Owner's manual. The duration of the display can be set via "adaptation" of the Climatronic control module using the Vehicle Diagnostic Tester in the "Guided Fault Finding" function.

• In the case of Comfort vehicles, the currently selected functions are displayed by the Climatronic control module, on the display of the control head and on the Multi Media Interface (MMI) display. The duration of the display can be set via "adaptation" of the Climatronic control module using the Vehicle Diagnostic Tester in the "Guided Fault Finding" function.

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

• If there is a condition in which 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, in the Memory seat/steering column adjustment control module (J136) or in the Front passenger memory seat control module (J521). In this vehicle information is currently not always sent via the data bus to the Climatronic control module. Check using the Vehicle Diagnostic Tester in the "Guided Fault Finding" function.

• If there is a problem with the seat heating or seat ventilation, first read out the event memory of the control modules which activate seat heating and seat ventilation using the Vehicle Diagnostic Tester in the "Guided Fault Finding" function.

• If a new Climatronic control module, was installed and the basic setting was not performed, A/C system regulation is limited and a malfunction about this is stored in the event memory. Check using the Vehicle Diagnostic Tester in the "Guided Fault Finding" function.

After replacing the Climatronic control module, perform the following work using the Vehicle Diagnostic Tester in the "Guided Fault Finding" function:

- Check the coding.

- Perform the basic setting.

- Check the adaptation as necessary.

- Read out the event memory and erase any displayed entries.