Audi Workshop Service and Repair Manuals

Special tools and workshop equipment required

• ◆ V.A.G 1526 A
• ◆ V.A.G 1594 A
• ◆ V.A.G 1598/31
• ◆ VAS 5051 with VAS 5051/1

• or

• ◆ V.A.G 1551 with V.A.G 1551/3 A

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:
• ‒ Under heavy acceleration (full throttle in 1st gear)
• ‒ In emergency running mode (back-up)
• ‒ When the "Basic setting" function is started (function 04)

Requirements for test:

• ● Air conditioner okay
• ● No faults stored in fault memory of engine control unit
• ● Vehicle at room temperature
  (above +15 °C)

Test sequence

• ‒ Connect vehicle diagnostic, testing and information system VAS 5051 (or fault reader V.A.G 1551) and select engine electronics control unit by entering address word "01" ( .)
  When doing this the engine must be idling

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

• ‒ Enter "050" for Display Group 050 and confirm entry with Q key.

• ‒ Switch off air conditioner.
• ‒ Specification for display zone 4: "Compr.OFF"
• ‒ Switch on air conditioner by pressing "AUTO" key and select maximum warm or cold air setting. The compressor should run.
• ‒ Specification for display zone 4: "Compr. ON"

• ‒ Floor and release the accelerator quickly (short blip).
• ‒ Specification for display zone 4: The display should change from "Compr.ON" to "Compr.OFF" for a few seconds (air conditioner compressor shut-off during acceleration).

If the readout in display zone 4 is not as described:

• ‒ Connect test box V.A.G 1598/31 to wiring harness for engine control unit. Do not connect to the engine control unit itself.
  => Page 24-16.
• ‒ Test for open circuit and short to positive or earth in the following wiring connection:

• ‒ Rectify short circuit or open circuit if necessary.
• ‒ If there are no faults in the wiring, test operation of air conditioner.

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