96 S10 AC Issues

[NeoDrake]

I recently took a trip, short run, but had to replace my starter while I was there, ( I know this should have NOTHING to do with my problem, however since it was the only thing different, I felt I should post it) On the way down, the AC worked fine, after replacing the starter however, I had no Air Conditioning. After getting back home to my tools, I checked the freon level, and it was fine, same with the a/c fuse in the fuse panel. Next, I checked for voltage on the two wires connecting to the compressor, with the a/c switch engaged and disengaged, there was none. So the clutch isn't engaging, and the parts store DOES show an AC Control Relay, as a possible replacement part, however with no book, I couldn't tell you WHICH of the four relays I see under my hood, on the firewall on the passenger side, that it might be. Any suggestions would be greatly appreciated in troubleshooting this issue.

[MT-2500]

Originally Posted by NeoDrake

I recently took a trip, short run, but had to replace my starter while I was there, ( I know this should have NOTHING to do with my problem, however since it was the only thing different, I felt I should post it) On the way down, the AC worked fine, after replacing the starter however, I had no Air Conditioning. After getting back home to my tools, I checked the freon level, and it was fine, same with the a/c fuse in the fuse panel. Next, I checked for voltage on the two wires connecting to the compressor, with the a/c switch engaged and disengaged, there was none. So the clutch isn't engaging, and the parts store DOES show an AC Control Relay, as a possible replacement part, however with no book, I couldn't tell you WHICH of the four relays I see under my hood, on the firewall on the passenger side, that it might be. Any suggestions would be greatly appreciated in troubleshooting this issue.

You forgot to tell us if a 2.2 or 4.3 engine.
Which is it?

Have you checked the fuses for 12 volts both sides?
Both AC fuse and AC compressor fuse?
If not sure on what relay is what or they have been switched in position.
I always ID the relay by the wires going to it.
Compressor relay.
Should be dark/green and orange that should be hot key on from ac compressor fuse and a pink wire and a dark green/white wire.

Also in the wiring and control circuit there is AC controls to PCM/VCM and low and high pressure switches and VCM AC request to compressor relay.

Post back what you find.

[NeoDrake]

Sorry, its a 2.2L, 4cyl, I've been able to locate the high pressure switch, however, calling my local chevrolet dealership, they said there is a low pressure switch on the accumulator, however, on my low pressure line, there are NO switches, I've followed the line from compressor to firewall. Going to see if I can identify the relay you suggested, and check for voltage at the fuse panel, however I could only find one fuse that said anything about AC, will look again when I check for power. Thanks for your help, and I'll keep you posted

[NeoDrake]

Ok, found both fuses, one marked heater/ac, the other marked ac compressor, 12v at each of them, found the relay based off of colors of wires you posted, i have 12v across the dark green/orange, however, its a CONSTANT 12v....nothing interrupts it, pulling either fuse, or shutting off the fan/ac switch. Unless I misunderstood what you wrote, that doesn't fully make sense to me. Will be buying and trying a relay tomorrow I guess, to see if that's the problem. Thanks again for the help.

[MT-2500]

Originally Posted by NeoDrake

Ok, found both fuses, one marked heater/ac, the other marked ac compressor, 12v at each of them, found the relay based off of colors of wires you posted, i have 12v across the dark green/orange, however, its a CONSTANT 12v....nothing interrupts it, pulling either fuse, or shutting off the fan/ac switch. Unless I misunderstood what you wrote, that doesn't fully make sense to me. Will be buying and trying a relay tomorrow I guess, to see if that's the problem. Thanks again for the help.

The dark green feeds compressor clutch.
If it has 12 volts the compressor clutch should be on.

How many wires and what color to relay have 12 volts before ac turned on?
Gauge fuse 4 feeds pink wire to relay with 12 volts key on.

Pink and orange wires to relay should be have 12 volts.
Then when ac is turned on the relay switches 12 volts to dark green compressor clutch feed.

A lot of times you can swap relays with no to test relay.