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Hello, I'm Chris. Thanks for visiting Just Answer.
Sorry for the long wait.Many techs have looked at your post and have not felt comfortable helping. This area of concern is not my strongest point but I will try to help as best I can at least with some information. I have access to a lot of repair guides so I should be able to at least do something to aid you if your still needing help and willing to let me try.Once I post an answer you will be prompted to rate me, not the site or wait time, or the news in my answer. Please let me know exactly what you need from me so I can earn a good rating. Chris .
so what is your reply on a/c 1990 buick reatta
chris have no idea how to read your findings ,you got my money on hold and i have no answer
send me a e-mail so i can respond
See the diagram below.
A few things can be wrong:
Faulty AC clutch
Faulty pressure switch
Bad signals to the relay
You need to check the compressor clutch plug while its commanded on to see if its getting power and ground, if its is but not running then the compressor clutch is weak or has an excessive air gap. If your missing power then check the relay pins 4 and 2 should be power from the fuse and pressure switch and BCM. Pin 5 needs to be ground from the ECM.