94 GMC A/C long standing problem question

Old 09-28-07, 04:41 PM
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94 GMC A/C long standing problem question

1994 GMC C1500 R134a
I'm trying to help a friend figure out what the issue is with his a/c. He said his a/c hasn't worked in years after the compressor clutch locked up and broke his belt and he can't remember how cold it was blowing around that time (years ago). All he did since then was replace the clutch to be able to put a belt on it. I didn't ask if he put on the clutch or what but figure he did because a shop surely would have at least told him what the problem is. I came into this picture just days ago when I learned he was trying to charge the system with one of those home kits but it would not take a charge at all (so I was told). I don't know much but here is what we did:
With the engine running and a/c on high nothing happened. I unplugged and jumped the low pressure switch and the rpm's increased but the compressor did not engage. I was thinking even if it was low/empty that would let me see if the compressor was functional (am I wrong?).
I guess we need to start at what made the a/c clutch lock up in the first place (which is where this all started) and go from there.........The only gauges I have are for the R12 era (because someone gave them to me and you never know when you'll need them). A neighbor had a gauge I guess came w/ a home kit so for knowledge sake I put it on the low? pressure fitting, it gave a reading of low which to me says there is some pressure there. Where to go from here? There are two connectors on the compressor, one nearest the pulley and one on the back. If I remember from my '94 the front supplies power to the compressor.
Old 09-28-07, 07:20 PM
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The A/C compressor has most likely seized, which caused the belt to snap.

Without the compressor running, it will not charge.

Jumper the compressor, I believe the pos + is the rear wire.
Old 09-28-07, 07:55 PM
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the front connector supplies power to the compressor, the rear connector on the back of the compressor is the high pressure cut out switch.
would agree he should of replaced the whole compressor as compressor failure likely caused the clutch to burn up to begin with along with a new orfice tube and drier wouldnt really expect it to work for very long if at all if he just replaced the clutch
if the a/c light is flashing you may need to disconnect the battery for a few seconds then reconnect to get the compressor to engage.

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