A/C Help
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Teching In
Joined: Apr 2007
Posts: 8
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A/C Help Though this doesn't seem like the time of year to be asking for A/C help up in New Jersey area but I finally got the money to purchase my own set of tools, instead of using my friends, and can now work on anything I want. My 1995 Trans Am has 150,000+ miles but the motor only has around 50,000 (was replaced by previous owner). Anyways, would like some advice about tackling my A/C issue because I have little clue as to where to begin. Basicially it does not turn on at all and I checked the relay to see if it was blown and it wasn't. Would like to know how next to go about diagnosing the problem.
Preciate the help
Preciate the help
Do you have enough freon in the system? I'm not 100% sure on our cars but I know some systems won't allow the compresser to turn on unless there is freon in the system. Has the AC ever worked since you owned it? Can you hear it "click" or see the compresser engauge when you turn on the AC?
you will need to check your freon level first, as already said the compressor will not come on if its low. its a safety so you dont burn it up, if you want to see if it engages unplug the battery for a min or two plug it back in and turn on the air an listen for the compressor to kick on. that wont mean the it is good but will let you know if it is engaging or not. and if you havent ran it in a while make sure you get the oil for the system as well
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On The Tree
Joined: Nov 2007
Posts: 130
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The PCM picks the A/C clutch... you need some freon in the system to let the PCM sense some A/C pressure (refrigerant in system) and pick the A/C clutch. One can (12oz) in a dead empty system will provide enough pressure. Our a/c pressure switch to the PCM is a 3 wire sensor (+5 from PCM, Ground from PCM, and a pressure signal to the PCM) so you can't jumper the sensor like in old cars to dummy up pressure for testing. What you can do is pick or jumper around the A/C relay in the relay box and make sure the a/c clutch picks and the compressor spins. However only pick it momentarily as running it w/o refrigerant will burn it out pretty fast. Ref http://shbox.com/1/hvac_compressor_control.jpg this is for a '94-95 you would remove relay , turn on key and jump B1 to B4 to pick the clutch, or ground B5 with relay installed to dummy up signal from PCM and the test relay. Also the relay is swappable with the fan relays if suspected. Or as stated previously buy a can of refrigerant with a gauge attached for 12 bucks and see if you have pressure first ?? If you have pressure it's can be the fuse to relay, bad relay, open clutch, defective clutch (picks but wont engage compressor), bad pressure sensor to PCM or bad PCM which is very, very rare.
Last edited by bobdec; Jan 6, 2009 at 03:50 PM.