Checking the air conditioner compressor shut-off: Audi 2.0 (AAD)

Note:

The air conditioner compressor is shut off by the engine control unit on accelerating from standstill and from low vehicle speed for approx. 12 seconds. If the accelerator pedal is released sooner, the time is reduced to min. 3 seconds.

Test requirements:

No faults stored in fault memory
Vehicle at ambient temperature (warmer than + 15 oC)
Air conditioner system OK
Vehicles with automatic gearbox: Selector lever in position P or N

Test sequence

Start engine and run at idling speed.
Switch on air conditioner system.

Briefly operate full throttle, the engine must not reach its maximum speed.
Air conditioner compressor must stop for a few seconds (visual inspection)

If the conditioner compressor is not switched off:

Read measured value block 0
⇒
1
2
3
4
5
6
7
8
9
10
Read measured value block, display group 000, engine at idling speed =>Page
01-44
.
Check display in display zone 9.
Specification: 5

Switch on air conditioner system.
The value must increase to 13.

Briefly operate full throttle, the engine must not reach its maximum speed.
The value must drop briefly.

If the specification is not obtained:

With the ignition switched off, use adapter V.A.G 1598/3 to connect test box V.A.G 1598 A to plug connection of engine control unit (control unit remains disconnected) => Page
25-9
.

Check for open circuit and short to positive or earth in the following wiring connections:

Test box / V.A.G 1598 A / Socket · Magnetic clutch control unit -J153 / / Contact · Operating and display unit / -E87 / Contact
33 · => Current Flow Diagrams, Electrical Fault-Finding and Fitting Locations

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

=> Heating, Air Conditioner; Repair Group 87; Air conditioner; Servicing components of the manually controlled air conditioner
Heating, Air Conditioner
Air conditioner
Servicing components of the manually controlled air conditioner

=> Heating, Air Conditioner; Repair Group 87; Air conditioner; Components and control of the fully automatic air conditioner
Heating, Air Conditioner
Air conditioner
Components and control of the fully automatic air conditioner

If both air conditioner and wiring OK:

Replace engine control unit => Page
25-12
.