Audi Workshop Service and Repair Manuals

Notes:

• ◆ When the air conditioner is switched on a positive signal is sent to contact 10 on the engine control unit.
• ◆ The signal causes the engine control unit to maintain a constant idling speed despite the varying power requirement of the air conditioner.

Test conditions

• ● Air conditioner functioning properlyo
• ● No faults recorded in air conditioner fault memory
• ● Interior temperature of more than +15 °C

• ‒ Connect fault reader V.A.G 1551 .
• ‒ Start the engine (operating temperature).
• ‒ Switch off rear window heating.
• ‒ Select "Read measured value block" (function 08) and Display Group 19.

Display zone 1: Idling speed

Display zone 3: Signal from air conditioner

Display zone 4: Air conditioner compressor operating status

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

Display zone 3 should read "1".

Display zone 4 should read "1" (air conditioner compressor on).

Apart from a brief drop in revs, the idling speed should remain constant.

• ‒ → If the readouts are not as specified, switch off the engine and connect test box V.A.G 1598/22 to wiring harness for engine control unit => Page 24-8.
• ‒ Test for short or open circuit in wiring between contact 10 on engine control unit and air conditioner operating and display unit E87 using current flow diagram.

=> Current Flow Diagrams, Electrical Fault Finding and Fitting Locations

• ‒ If there are no wiring faults, test the operation of the air conditioner operating and display unit.

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