A/C System Control And Regulation Notes

NOTE:

If there is a malfunction in the Air Conditioning (A/C) system, first check the event memory of the front A/C display control head, the Climatronic Control Module -J255- (and the Rear A/C Display Control Head -E265-) Vehicle Diagnostic Tester in the "Guided Fault Finding " function. If another control module displays an instruction to read out the event memory, also read out the event memory for this control module (for example the Vehicle Electrical System Control Module -J519-, the Comfort System Central Control Module -J393-). Certain components of the A/C system (for example, the Air Conditioning (A/C) compressor Regulator Valve -N280-, the A/C Pressure/Temperature Sensor -G395-) are not evaluated directly by the Climatronic Control Module -J255- or their measured values are not evaluated directly by the Climatronic Control Module -J255-, refer to Vehicle Diagnostic Tester in the "Guided Fault Finding " Function.

If no malfunction is displayed, read the relevant measured value block for the front A/C display control head, the Climatronic Control Module -J255- (and the Rear A/C Display Control Head -E265-) and activate a potentially problematic component via the "output DTM" function see Vehicle Diagnostic Tester.

The function "electrical testing" is not described in this Repair Manual. Perform electrical testing via "Guided Fault Finding " function, here can also be found notes on the functions which should be tested, refer to Vehicle Diagnostic Tester.

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.

Temperature-dependent resistance values of the various temperature sensors are stored in one table, these can be called up via the "Guided Fault Finding " function see Vehicle Diagnostic Tester.

Electrical checking of the various control motors is described in the "Guided Fault Finding ", refer to Vehicle Diagnostic Tester.

Repair work on refrigerant circuit, refer to REFRIGERANT CIRCUIT .

Perform the following work after completion of repair operations:

-- Check the event memory of the front A/C display control head, the Climatronic Control Module -J255- (and the Rear A/C Display Control Head -E265-) and erase any displayed malfunctions see Vehicle Diagnostic Tester.

-- Check the coding of the front A/C display control head, the Climatronic Control Module -J255- (and the Rear A/C Display Control Head -E265-), refer to Vehicle Diagnostic Tester.

-- Check the adaptation of the front A/C display control head, the Climatronic Control Module -J255- (and the Rear A/C Display Control Head -E265-), refer to Vehicle Diagnostic Tester.

-- Perform the basic setting of the front A/C display control head, the Climatronic Control Module -J255- (and the Rear A/C Display Control Head -E265-), refer to Vehicle Diagnostic Tester.