Looking to see if I can get some help with my AC. It's a 87 Trans Am, engine from a 91 Z28 with accessories. Replaced the compressor for the 91 style about a year or so ago. At the time of transfer, I didn't replace any o-rings or orfice tube, and used the accumulator from the 91. Mistake, I know. Had the system vacuumed and recharged, worked great for awhile but had issues with air only coming from the defrost vents. Fast forward to now, got the hvac system in order but now trying to get AC again, system was pressurized, but with air. Every time I'd try to add freon, it wouldn't take and peg the freon gauge to the red. Replaced accumulator, orfice tube, and redid all o-rings today. Vacuumed the system, held vacuum just fine so tried to charge. It took a 12oz can of freon and oil, but the system is still reading high pressures and comp clutch isn't kicking in. Jumped the low pressure switch and it was on and off but can't get it to come on anymore. All connections are good so I'm thinking maybe the comp clutch is done for? Either way, why would the system pressurize with air?

 

Sounds like you don't have enough refrigerant in it yet.

As to why it won't come on, I'd suggest checking the quality of your "short". Might have burned up. I use a piece of 18 ga wire with male slide terminals, and after disconnected the LP shutoff connector, plug the short into the connector.

And of course make sure the plug isn't intermittent at the clutch connector or at the HP cutoff sw.

Clutch is probably OK.

 

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I'm actually having some of the same problems with mine.

The clutch does not seem to engaging, I'm not 100% sure if the clutch even works. What is the method of running the jumper for testing? I want to try and troubleshoot and see if I can get this system running again.

Thanks!

 

Not much more to say about it... should be totally self-explanatory.

 

This connector located on your accumulator on your passenger side firewall. Disconnect the connector from it (silver canister can't miss it), and put use a wire between the two spade connectors inside the connector. You want to make sure your AC is set to NORM or MAX and blower on HIGH. This should engage your compressor clutch.

 

 

I got my issues sorted out. Was a bad high pressure switch on the compressor. Swapped that out along with a new compressor, accumulator, orfice tube. Had the system vacuumed and recharged. Blowing cold now.

 

Yeah that switch flakes out a lot... it's not in your pic of course... the center pin gets spread out and then the plug doesn't make a good connection. Not hard to troubleshoot if you get to that point; since it's on the ground side of the clutch circuit, then if there's 12V on both sides of the clutch connector, then everything that feeds 12V to it is OK, but it isn't making it to ground, which then points at the HP cutoff.

LOTS of cars don't even have that switch. Probably wouldn't even be too much of a sin to cut the conn off the end of that wire and put a ring terminal on it and stick it under a bolt somewhere; probably wouldn't even get you sentenced much below about the 3rd or 4th level of Hell by itself, unless of course you had done something else even worse like maybe put on an Edelbrock carb and left the stock distributor, in which case it would just be an aggravating circumstance.