Testing the air conditioner compressor shutoff: Audi 2.0 (ABK, ADW)

ADW
Note:

The compressor cut-off for the air conditioner is carried out in two directions ("in" and "out"):

In: Voltage is supplied to pin 13 just before the air conditioner compressor is switched on. The Digifant control unit opens the idling speed stabilisation valve slightly more in order to compensate for the additional load as result of the faster idling speed.
Out: When accelerating from a stationary start or from a low speed, the AC compressor is switched off for up to 12 seconds by the Digifant control unit.
In addition, the compressor is switched off when starting and if faults exist in the idling speed stabilisation.

Special tools, testers and auxiliary equipment required

Hand-held multimeter V.A.G 1526 or V.A.G 1526 A
Adapter set V.A.G 1594 A
Test box V.A.G 1598/18

Test requirements:

Air conditioner system OK
No faults stored in fault memory
Vehicle at ambient temperature (warmer than + 15 oC)

Start engine and run at idling speed.
Switch on the air conditioner (the AC compressor should run):
Manually controlled air conditioner Press the "AC" button.
Fully automatically controlled air conditioner Press the "AUTO" button, set the temperature to "LO" and blower speed to "HI".

Briefly operate full throttle, the engine must not reach its maximum revs.
Test visually to determine whether the AC compressor stops for a few seconds.

If the AC compressor is not switched off:

Switch off the ignition and carry out the following test:

Vehicle with manually controlled air conditioner:

With the ignition switched off, connect test box V.A.G 1598/18 to connector for engine control unit => Page
24-16
.

Set hand-held multimeter V.A.G 1526 to voltage measuring range (20 V direct current) and connect to engine earth and contact 13 and 42 on connector using test leads from V.A.G 1594 A.
Switch the ignition on.
Switch on the air conditioner by pressing the "AC" button.
Specification: greater than 8 V (after about 10 seconds)

If the specified values are not obtained:

Test the wiring connection between contact 13 of the connector of the Digifant control unit and the magnetic clutch control unit -J153 for open circuit or short circuit according to the current flow diagram.

If the wiring connection is OK test the signal for the magnetic clutch control unit:

=> Heating, Air Conditioner; Repair Group 01; Performing self-diagnosis - Manually controlled air conditioner; Performing final control diagnosis
Heating, Air Conditioner
Performing self-diagnosis - Manually controlled air conditioner
Performing final control diagnosis

Vehicles with fully automatically controlled air conditioner:

Perform final control diagnosis:

=> Heating, Air Conditioner; Repair Group 01; Performing self-diagnosis - Fully automatically controlled air conditioner; Performing final control diagnosis
Heating, Air Conditioner
Performing self-diagnosis - Fully automatically controlled air conditioner
Performing final control diagnosis