New Compressor Won't Turn On

A/C in my 94 Lumina APV was blowing hot air and I noticed compressor clutch would not engage.

I checked fuses, they were fine, so I replaced the compressor, after filling it with refrigerant oil, vacuummed the system, and added a can of R-134a, still the compressor won't turn on no matter what setting I have the A/C on.

I checked all 3 electrical connections and they were tight. I even replaced one of the switched on the compressor when I put the new one in.

Any ideas?

Welcome to AF. One can of freon may not engage the compressor. Jump the pressure switch and try it again. Is this why you replaced the compressor, because the clutch wouldn't engage. Checked the compressor relay in the relay panel?

Welcome to AF. One can of freon may not engage the compressor. Jump the pressure switch and try it again. Is this why you replaced the compressor, because the clutch wouldn't engage. Checked the compressor relay in the relay panel?

Yes, the compressor had been replaced once before with a remanufactured one.

How do you jump the pressure switch? In the meantime, I'll try to make heads or tails of the relay panel. I am very new to auto AC repair, in case you didn't notice. So you might have to dumb it down for me:iceslolan

Welcome to AF. One can of freon may not engage the compressor. Jump the pressure switch and try it again. Is this why you replaced the compressor, because the clutch wouldn't engage. Checked the compressor relay in the relay panel?

Also, the low side pressure was reading 35psi after adding the one can. Shouldn't that be enough to make the compressor work?

I'm thinking either the sensor on the high side is bad, or, like you said, the relay is bad.

I also disconnected the electrical connecters and used a volt meter on all three electrical connectors going to the compressor and could not get any voltage on any of them with the AC on full blast in Max recirc mode.

Use this as a helper:
www.avigex.ca/xport/accompressorcontrol.jpg

THe difference with the 3.1 is only the fuse on the right is used for all.

Unplug both pressure switches and jump the connectors. THey are not in series with the clutch coil itself, nut are enable signal to the PCM.This should enable the PCM ...but this is not the only condition.

THen of course you have to make sure the relay receives the coil signal and is functional....then the power side of the relay must be HOT.

ANd..of course, one can of refrigerant is not enough...it may establish idle pressure but will fall down as soon as compressor starts , cutting the compressor...but then it should periodically cycle on and off......
THe correct refrigerant charge is 2.62 lb (42 oz) for front A/C and 3.50 lb (56 oz) for vehicles equipped with front and rear A/C evalorators.