Question about 1991 Pontiac Firebird

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My a/c compressor turns on and off rapeadly on any

My a/c compressor turns on and off rapeadedly on any setting and it vibrates part of the belt thats near it wen it turns on for the 3 secondsand shuts off then turns back on instantly i need help?

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The turning on and off is caused by low freon, you still have some in there, the pressure fluctuates a bit when it kicks on. The pressure builds up just enough to pass the minimum level to kick on the compressor, then as it kicks on and allows the freon to flow, the pressure drops a little, causing it to fall below the threshhold and causing it to shut off, and the cycle then repeats. You probably have a slow leak, if it still has enough to kick on intermittently. A 12oz can of freon should bring it up to the point where the compressor will stay on, it may take a bit more to fill it though. This is the most common cause, although you cant rule out the possibility of compressor failure. But this is the cheapest easiest route to check. After you get the compressor to stay on, check and see if your belt is still having the vibrating issues, if so, with the engine off check its tension by pressing on the belt in between pulleys, there should be minimal movement.

Posted on Sep 24, 2009

Testimonial: "thanks i put it in i found the leak its a line and fixed the vibration caused by lose compressor guy who preveiously owned it forgot to tighten it"

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First change the belt with a correct sized one and have the quantity of refrigerant gas & top-up if required...................sodeep

Posted on Sep 24, 2009


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