Control Module HVAC: Description and Operation
Front A/C Control Head Control Module, Climatronic
- Removing and installing front A/C control head Climatronic Control Module (J255). Refer to=> [ Front A/C Control Head Climatronic Control Module ] Front A/C Control Head Climatronic Control Module
• Front A/C control heads cannot be exchanged as usual. Component protection becomes active once a Climatronic Control Module (J255) front A/C control head is programmed in a vehicle. Vehicle diagnosis, testing and information system VAS 5051 in "Guided Fault Finding" function.
• If a Climatronic Control Module (J255) front A/C control head with active component protection is installed in a different vehicle, only the functions necessary for vehicle safety can be selected. Comfort functions can no longer be selected Vehicle diagnosis, testing and information system VAS 5051 in "Guided Fault Finding" function.
• Component protection can only be canceled by entering specific vehicle data Vehicle diagnosis, testing and information system VAS 5051 in "Guided Fault Finding" function.
• Front A/C control head Climatronic Control Module (J255) may also be designated "Climatronic Control Module -J255- " in wiring diagrams.
• Use the correct allocation when replacing the Climatronic Control Module (J255) A/C control head.
• Different versions of front A/C control head Climatronic Control Module (J255) on vehicles with or without seat heater, seat heating with or without seat ventilation. Part number index must therefore be heeded. .
• After installing the Climatronic Control Module (J255) A/C control head, perform an A/C system basic setting according to the instructions from the vehicle diagnosis, testing and information system VAS 5051 in the "Guided Fault Finding" function
• If a new Climatronic Control Module (J255) front A/C control head is installed and basic setting is not performed, the control head will have limited ability to regulate and that will be displayed as a malfunction in the DTC memory vehicle diagnosis, testing and information system VAS 5051 in the "Guided Fault Finding" function.
• The Climatronic Control Module (J255) front A/C control head can be activated for up to approximately 30 minutes after switching the ignition off by pressing the On/Off button. The operating time depends on the battery level. It is a maximum of 10 minutes. => Owner's Manual
• Display fields and control buttons on front A/C control head Climatronic Control Module (J255) are illuminated by light emitting diodes (LEDs, cannot be replaced).
• If Instrument Panel Interior Temperature Sensor (G56) sends incorrect measurements, check intake grille on panel of front A/C control head Climatronic Control Module (J255) (must not be sealed) and function of Interior Temperature Sensor Fan (V42).
• The selected functions are displayed by illuminated LEDs in the various buttons of front A/C control head Climatronic Control Module (J255).
• The units for the front A/C control head temperature display °C or °F are transmitted by the MMI via the Comfort databus system, which then assigns the setting that was entered => Owner's Manual and => "Infotainment/MMI" Owner's Manual.
• In model year 2003, front A/C control head, Climatronic Control Module (J255) was installed with software number " 026". With these front A/C control heads, Climatronic Control Module (J255), settings assigned to a specific person via fingerprint may be lost when starting the vehicle via "one-touch memory ". Service installation of front A/C control heads Climatronic Control Module (J255) with this software number is therefore not permitted on vehicles with "one-touch memory".
• Pressing the buttons on the Climatronic Control Module (J255) front A/C control head for an extended period of time, for example if an object is lying on them, can cause a fault to be stored in the DTC memory indicating the buttons are stuck. If necessary, check the function of the buttons and erase the DTC memory if no malfunction is found.
• Front A/C control head Climatronic Control Module (J255) is not connected to terminal "15", therefore after voltage supply interruption (via connector - E -), it is necessary to wait at least 30 seconds to protect electronics until remaining connections are disconnected.
• Two rotary knobs are attached. They can be removed and replaced separately.
Perform the following steps after replacing Climatronic Control Module (J255) front A/C control head Vehicle diagnosis, testing and information system VAS 5051 in "Guided Fault Finding" function.
- Check encoding.
- Implement basic setting.
- Check adaption
- Check the DTC memory.
• From model year 2009, the Climatronic Control Module (J255) front A/C control head with part number 4E0 820 043 from index "J" will be installed as a running change. On vehicles with these front A/C control heads, the screen in the "MMI" display will not switch to "A/C system" when the buttons and knobs on the front A/C control head are pressed. The selected A/C system functions are shown in the running display. Certain A/C system functions in these vehicles are selected and activated with the rotary knobs on the "MMI" unit => Owner's Manual and => "Infotainment/MMI " Owner's Manual. On these front A/C control heads, the Setup button is replaced with the A/C button and the ON /OFF button is replaced with the OFF button => Owner's Manual.
• On vehicles that have a Climatronic Control Module (J255) front A/C control head without the Setup button, select the additional functions through the "Multi Media Interface (MMI) terminal" => Owner's Manual and => "Infotainment/MMI" Owner's Manual.
• Make sure the Climatronic Control Module (J255) front A/C control head is allocated correctly to the Information Electronics Control Module 1 (J794). There are different versions. If the allocation is incorrect, various A/C system functions cannot be displayed and selected in the MMI.