Vehicles With Manually Regulated A/C System

Vehicles With Manually Regulated A/C System

A/C Control Module (J301) activation

• From MY 2009, as a running change, the Climatronic control module (J255) (or control modules for seat heating) is being installed, whereby the specified temperature is set to a lower characteristic line. Refer to Vehicle diagnosis, testing and information system (VAS5051B) in "Guided Fault Finding" function and to the Electronic Parts Catalog.

• On vehicles with manual climate control system, activation of heated seats is not monitored by the A/C Control Module (J301) electronics, therefore malfunctions are not stored in DTC memory.

• The A/C control module (J301) provides a voltage via the heated driver seat adjuster (E94) and heated front passenger seat adjuster (E95) (a potentiometer is operated via the respective knurled wheel - C -).






• The voltage supplied by A/C Control Module (J301) - A - with seat heater switched on is dependent on the knurled wheel position and on the vehicle voltage supply, it is in the range of less than 0.5 volts in position 0 to approximately 10 volts in position 5 (measured to Ground -GND- e.g. at connector - B - terminal 20) with engine running. The voltage is transferred via connector - B - (from terminal 13 to Driver Seat Heater Control Module (J726) and from terminal 12 to Front Passenger Seat Heater Control Module (J727) ).






• Resistance of seat heater potentiometer is dependent on the knurled wheel position, it cannot be measured using workshop equipment.

• Check function of seat heater and service it.