A/C

FAULT DIAGNOSIS, A/C

Fault Symptom.
The A/C compressor does not work.

NOTE: Diagnostic trouble codes P145O and P1451 will be generated when the control module output (pin 25) is open or shorted to ground/batt+.
The diagnostic trouble code is generated by electrical faults.
Fault diagnosis in this section deals with other faults.

Diagnostic Procedure.
1. Connect the Scan Tool.
Start the engine and run it at idling speed.
Select "READ ON/OFF".
Select "AC REQUEST".
Activate the compressor from the dashboard:
- Manual A/C: fan ON and A/C button depressed
- ACC: select AUTO
The Scan Tool should show "ON" and engine rpm should increase.

If this does not happen the fault is before the Motronic. In such case, continue fault diagnosis in the Climate control system.

2. Switch OFF the engine.
Turn the ignition switch to the ON position.
Select "ACTIVATE".
Select "AC RELAY". This command activates the A/C relay at a frequency of 0.5 Hz for 30 seconds.
- The A/C relay and compressor engagement should now both be heard.

If this is not the case, the fault is after the Motronic. Continue fault diagnosis in the Climate control system.