Audi Workshop Service and Repair Manuals

Notes:

• ◆ The air conditioning compressor signal informs the engine control unit that the compressor will be switched on in 140 ms.
• ◆ The engine control unit can send a signal via the same wire to shut off the air conditioner compressor.
• ◆ The engine control unit will shut off the air conditioning compressor in the following cases:
• ‒ During powerful acceleration (full throttle in first gear)
• ‒ In the emergency programme (emergency running mode)
• ‒ After initiating of basic setting (Function 04)

Test requirements:

• ● Air conditioning system OK
• ● No faults recorded in fault memory of engine control unit
• ● Vehicle at ambient temperature (warmer than + 15 °C)

Test sequence

• ‒ Connect the vehicle diagnostic, testing and information system VAS 5051 or fault reader V.A.G 1551 and select engine electronics control unit with "Address word" 01
  For this purpose, the engine must be running at idle speed.

• ‒ Enter "08" to select the function "Reading measured value block" and confirm entry with Q key.

• ‒ Enter "050" for "display group number 050" and confirm with Q key.

• ‒ Switch off air conditioner.
• ‒ Specified value for Display zone 4: Compr. OFF
• ‒ Switch on air conditioning with "auto" button and set air conditioning to maximum cooling/ heating. The compressor must run.
• ‒ Specified value for Display zone 4: Compr. ENG.

• ‒ Abruptly floor the accelerator pedal and release again (brief burst of throttle).
• ‒ Specification for display zone 4: Display switches for several seconds from "Compr. ON" to "Compr. OFF" (compressor shut-off on vehicle acceleration)

If the readout in display zone is not as described:

• ‒ Connect the V.A.G 1598/31 test box to wiring harness leading to engine control unit; the engine control unit should not be connected => Page 24-19.
• ‒ Check for open circuit and short to positive or earth in the following wiring connections:

• ‒ Rectify any open/short circuit as necessary.
• ‒ If there are no faults in the wiring, check the operation of air conditioning.

=> Heating, Air Conditioner; Repair group 01; Self-diagnosis for air conditioner