jumping A/C compressor???

[Schrade]

Where's the 12 volt input on a GM A/C compressor, to test by jumping?

It looks like there's two connectors on this friend's compressor; one just behind the pulley wheel, and the other on the back of the unit.

I don't remember that either one had a red wire; is there a third connector somewhere else?

[silicon212]

Originally Posted by cbec1999

Where's the 12 volt input on a GM A/C compressor, to test by jumping?

It looks like there's two connectors on this friend's compressor; one just behind the pulley wheel, and the other on the back of the unit.

I don't remember that either one had a red wire; is there a third connector somewhere else?

What model compressor? What year?

Usually the green wire on the connection behind the pulley will be your compressor clutch hot. I'm not familiar with all models of compressors that GM uses, but two that I do know are the A6 (long cylinder shaped, common on older cars) and the R4 (large diameter, short length). Older expansion-valve type A/C has a fuse inline with the clutch power, there's a lead that comes off of this to the back of the compressor. This is to blow the fuse in the event that freon pressure drops too low (and can burn up the compressor). Newer, orifice-tube type A/C (the kind with a large accumulator on the outside of the evap coil housing) doesn't have this fuse type setup as a pressure switch (on the accumulator) takes over the function of the fuse. This setup only has the connector behind the pulley on the compressor.

If you're having a problem with the compressor clutch not engaging, the first step is to use a manifold gauge on the system to ensure that there's pressure. If not, evacuate and refill with the proper amount of oil, and the proper refrigerant.