air conditioner compressor will not kick on

1999 CHEVROLET LUMINA
85,000 MILES • 3.1L • V6 • 2WD • AUTOMATIC
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JSTEBBINS
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System charged, pressure switch good (new), relay good (new) air conditioner compressor will not kick on on its own. I can bypass the relay and it blows cold air but will not run otherwise. Everything is sill like new on this car. No corrosion on the fuse relay blocks/ connections, all fuses good. Anyone have anything similar?
Aug 4, 2016 at 5:33 PM
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WRENCHTECH
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Test your two fuses first. If the fuses check out okay, your next step will require a professional scan tool to look at data and determine if the PCM is getting the "ON" request from the Control Head. https://www.2carpros.com/images/external/78296762.gif
Aug 5, 2016 at 6:00 AM
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JSTEBBINS
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If it ends up being the PCM, can a used one be purchased and installed without reprogramming? Plug and go?
Aug 8, 2016 at 7:16 PM
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WRENCHTECH
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No, it can't but why would you even suspect the PCM. That is the least likely cause of your problem.
Aug 8, 2016 at 7:19 PM
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JSTEBBINS
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Because everything else has been replaced and is working . The cooling fans also kick on shortly after start up and run all the time whether the air conditioning is on or not . I am not saying that is the problem but after all that has been done it's pointing in that direction . I am thinking my next step should be getting it to someone who can stand the PCM and see what it is doing
Aug 9, 2016 at 9:08 AM
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WRENCHTECH
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As I said, that is not not likely at all. I live in South Florida and I have been repairing AC for over 40 years and I have yet to Replace a PCM for inop AC. You need someone with electrical knowledge to track it down by following the wiring diagram and a scanner.
Aug 9, 2016 at 12:56 PM