Australian Car Repair Issues? Ask an Auto Mechanic for Answers ASAP
Have you recharged with the correct weight of gas?
The pressure switch will not allow the compressor to operate if not within set parameters.
The switch, or wiring to the ECM could be faulty.
You need to look at ECM compressor data for further analysis.
I can't access the wiring like I used to when I worked for Holden, but that may change shortly.
You say both sides of the relay coil have nothing, as you would understand, one should be there while the engine is running, then the other appears after a switch request occurs.
Supplying 12v to 87 proves the output side of the relay wiring is fine.
We need to find which is truly missing, 86 or 85.
Has the fuse box (UEC, underhood electrical centre) been out at all?
Can you please check the 10mm bolts that hold it in?
The A/C relay would have ignition 12v to say 86, and the ECM provides ground to 85 after it receives a switch request from the HVAC facia panel.
Can you check tbe pressure sensor wiring, 5v ground and signal?
One will have 5v, one should have 0 ohms to ground, and the 3rd back probed will conected to the sensor should be about 2.5 volts.
I had one car that had no ground, and hence no a/c.
The sensor ground wire was broken from a car accident.
The sensor signal goes high volts, about 4.5 volts, and disables compressor operation due to the ECMs interpretation of high system pressure when it clearly isn't.
A Tech2 would help you with a data list.
I have Astras where the ECM is the faulty component.
I hope my suggestions to you are of some help.
Please post another question when you ready, and I'll keep my eyes open for it.
An ECM swap is easy for a Holden tech.
The ECMs need to be reset, which unlinks them from the immobilizer.
Then you swap them, and Tech2 relink to immobilizer.