Audi Workshop Service and Repair Manuals

Notes:

• ◆ The air conditioner 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 conditioner compressor in the following circumstances:
• ‒ Sharp acceleration (full throttle)
• ‒ In emergency running mode (back-up)
• ‒ If the coolant temperature exceeds 120°C

Test conditions

• ● Air conditioner functioning properly
• ● No faults recorded in fault memory of engine control unit
• ● Interior temperature of more than +15°C

Special tools, testers and auxiliary items

• ◆ Fault reader V.A.G 1551 (or vehicle system tester V.A.G 1552) with cable V.A.G 1551/3
• ◆ Adapter set V.A.G 1594
• ◆ Test box V.A.G 1598/22

• ‒ Connect fault reader V.A.G 1551
  .
• ‒ Start the engine.
• ‒ Select "Read measured value block", Display Group 020, engine at idling speed.

• ‒ Switch off air conditioner.

Display zone 4 should read "Compr.OFF".

• ‒ Switch on the air conditioner by pressing the "Auto" key. The compressor should run.

DIsplay zone 3 should read "A/C-High".

Display zone 4 should read "Compr.ON".

• ‒ Floor and release the accelerator quickly (short blip).

When the accelerator is floored quickly, the readout in display zone 4 should jump from "ON" to "OFF" for a few seconds (compressor shut-off during acceleration).

• ‒ If the display readout is not as specified, switch off the engine and connect test box V.A.G 1598/22 to the wiring harness for the engine control unit.

• ‒ → Test for open circuit and short to earth or positive in wiring between air conditioner and contact 8 on engine control unit using the current flow diagram.

=> Current flow diagrams, Electrical fault finding and Fitting locations binder

• ‒ If there are no faults in the wiring, test operation of air conditioner.

=> Air conditioner; Repair Group 01; Self-diagnosis for air conditioner