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Harv
Harv 9/26/2010
1993 Chevrolet G30 Hi-Cube 8Cyl5.7L - Engine
A/C clutch will not engage on new compressor
Purchased a new Replacement Brand compressor. Installed, evacuated system. When I try to charge the system the compressor clutch wil not engage. The pressure switch on the back of the compressor is closed reading .2 ohms. The clutch reads 4.4 ohms. There is a resistor across the green & black wires on the clutch connector reading about 1200 ohms. Reading 38 ohms black to ground and 44 ohms green to ground. compressor turns freely by hand. Old compressor work except bearings were bad. All wiring and fuses appear OK. Vehicle has 38000 miles. It is in the 50s outside. Is there a low temp cut out? The a/c on my Chevy Astro van works. Got me stumped.
2 Answers
  • dtrOlv
    dtrOlv 11/1/2010
    I just "rebuilt" the whole system on my 93 5.7L Silverado. The $15 pressure switch on the accumulator/resevoir did the trick. I thought it was leaking and just changed those seals because I could get the compressor kicking off and on with a Freon cart hoooked up filling it. But after a few minutes it quit. Tapping on that switch made it kick on again, and changing it did the trick. Pass the word, I've heard this same problem from many folks.
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  • dtrOlv
    dtrOlv 11/1/2010
    By the way, you can safely remove that switch without depleting pressure because of the check valve behind the switch. spit on the check valve after removing the switch and see if you notice the check valve leaking past the seat seal. if it's leaking there you have to bleed down the system and change the seat seal or entire check valve.
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