Audi Workshop Service and Repair Manuals

The increase in idling speed resulting from the air conditioner signal depends on the control unit version and is not activated in all vehicles.

The air conditioner signal informs the engine control unit that the air conditioner needs a higher idling speed in order to provide the desired interior temperature (both when cooling and heating).

• ‒ Connect fault reader V.A.G 1551 (V.A.G 1552) and select the engine electronics control unit using "Address word" 01. When doing this the engine must be running at idling speed.
  (Connecting fault reader and selecting engine electronics control unit .)

• ‒ Press keys 0 and 8 for the function "Read measured value block" and confirm entry with Q key.

• ‒ Press keys 0, 0 and 2 for "display group number 2" and confirm entry with Q key.

• ‒ Observe display in display zone 3, the air conditioner must not be switched on.

• ‒ Switch on air conditioner, press the "Auto" key and select the lowest temperature.
• ‒ Select the lowest temperature and highest blower speed. The air conditioner compressor should run.
• ‒ Check display in display zone 3.

If specified value is not attained:

• ‒ → Connect test box V.A.G 1598/22 to wiring harness for engine control unit .

The following wiring connections are to be checked for open circuits and/or short to positive or negative.

• ‒ Rectify any open/short circuit as necessary.