A?c problem
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Joined: Oct 2007
Posts: 85
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From: Mareeba Queensland
A?c problem
Hi there. I have an 87 auto c68the a/c clutch is cycling every five seconds.I have just replaced the low pressure switch and the blower control module and is full of gas.Any ideas men. Thanks Wayne
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Joined: Oct 2007
Posts: 85
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From: Mareeba Queensland
Melting Slicks
Joined: Sep 2008
Posts: 2,376
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From: Cherokee National Forest TN
Remove the connector from the low pressure switch & jump the connector with an opened paper clip. If the compressor runs continuously the system is low on freon. If it still cycles its over charged.
Race Director
Joined: Apr 2003
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From: moraga ca
Gauges are cheap at Kragens. Buy one and a can of c-12 or whatever we're using these days and fill it yourself if it reads low. If high, you're supposed to have it bled at an ac shop that has an evacuator or ...
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Joined: Oct 2007
Posts: 85
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From: Mareeba Queensland
Thanks Wayne
Le Mans Master
Joined: Dec 2000
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From: San Diego, Ca
Sounds like it's plugged up. Liquid refrigerant is metered into the Evaporator through a fixed, screened restriction called an orifice. When metal or debris (from a worn out compressor or Dryer that's falling apart because it's got the wrong gas in it) gets trapped in the screen, insufficient liquid reaches the Evaporator and what gets in flashes to a gas. That takes the oomph out of it and by the time it reaches the Low Pressure Switch, there's nothing to keep the contacts closed. The clutch circuit then opens and the clutch cycles off. You need to put a Manifold gage set on it and more than likely, take it apart and rebuild it. Don't put any more gas in it as the blockage backs it up creating more pressure on the high side. And if the High Pressure Switch fails, you'll blow a hole in something - like the hood or yourself.
Thread Starter
Advanced
Joined: Oct 2007
Posts: 85
Likes: 1
From: Mareeba Queensland
Sounds like it's plugged up. Liquid refrigerant is metered into the Evaporator through a fixed, screened restriction called an orifice. When metal or debris (from a worn out compressor or Dryer that's falling apart because it's got the wrong gas in it) gets trapped in the screen, insufficient liquid reaches the Evaporator and what gets in flashes to a gas. That takes the oomph out of it and by the time it reaches the Low Pressure Switch, there's nothing to keep the contacts closed. The clutch circuit then opens and the clutch cycles off. You need to put a Manifold gage set on it and more than likely, take it apart and rebuild it. Don't put any more gas in it as the blockage backs it up creating more pressure on the high side. And if the High Pressure Switch fails, you'll blow a hole in something - like the hood or yourself.
Thanks Wayne
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Le Mans Master
Joined: Dec 2000
Posts: 7,839
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From: San Diego, Ca
Confirm that it's plugged up first, but if the compressor was replaced because the old one seized, that's a good possibility; particularly if all the debris wasn't removed at the time of the replacement.. Assuming it is plugged up, the orifice can be cleaned or replaced. Replace the Accumulator. Flush all lines, Evaporator and Condensor with an appropriate flushing agent and/or consider replacing the Condensor because it's difficult to get all the crap out of it. Flush the compressor by draining any oil that's in it and putting in 4 ozs of whatever oil is compatible with the gas you are using. Turn the shaft a dozen or so times in one direction, then the other. Drain and repeat. Leave 4 ozs of oil in it. Put 4 ozs of oil in a new Accumulator and make sure the Accumulator is compatible with your gas. Pull a vacuum and recharge.
