AC Help
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Joined: Jan 2010
Posts: 62
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From: Columbia PA
AC Help
My ac was working a week ago. Then a couple days ago it was just blowing outside air temp air. The cooling fans turns on for engine temp but not for the ac and the ac clutch does not engage. There is r12 still in the system but not sure how much. i think it may but the pressure switch or a little low on r12 but i dont know. Any help will be great!
Drifting
Joined: Aug 2002
Posts: 1,775
Likes: 125
From: Birmingham AL
My ac was working a week ago. Then a couple days ago it was just blowing outside air temp air. The cooling fans turns on for engine temp but not for the ac and the ac clutch does not engage. There is r12 still in the system but not sure how much. i think it may but the pressure switch or a little low on r12 but i dont know. Any help will be great!
Le Mans Master
Joined: Dec 2000
Posts: 7,839
Likes: 22
From: San Diego, Ca
Not a good idea to just add gas. If you don't have gages, at least get the static pressure (compressor not engaged) from the Pressure Sensor with a scanner. It needs about .8 volts or 80 psi at 70 degrees which would indicate at least a 1/2 lb of gas. If it shows no volts or 0 psi, it's out of gas and since it was cold one day and then suddenly warm, look for a hole in the Condensor or a busted hose.
The system doesn't actually know the Low Side. It simply monitors how often the Low Pressure contacts open and close the Compressor Relay and if it's a rapid sequence, that's it's signal that it's low on gas. That also sets a trouble code. If there's no trouble code and there's static pressure, it may have plenty of juice and you simply have an open at the Low Pressure Switch which happens on GM a/c systems from time to time. Remove the connector from the Low Pressure Switch and use a DVM to see if the contacts are closed. If so, try holding the Connector on the switch or wriggling it around. If that gets it going you need a new connector.
The system doesn't actually know the Low Side. It simply monitors how often the Low Pressure contacts open and close the Compressor Relay and if it's a rapid sequence, that's it's signal that it's low on gas. That also sets a trouble code. If there's no trouble code and there's static pressure, it may have plenty of juice and you simply have an open at the Low Pressure Switch which happens on GM a/c systems from time to time. Remove the connector from the Low Pressure Switch and use a DVM to see if the contacts are closed. If so, try holding the Connector on the switch or wriggling it around. If that gets it going you need a new connector.
