Model: Grand Am
Engine Size: 4 cyl
Where's the low pressure switch on this car? I only see the pressure switch on the high side line into the condenser. I've looking on all the lines, and around the accumulator in the fender.
System is completely empty (0 psi), but no signs of oil leakage anywhere, all the connections are perfectly clean. Is there any common failure point on these cars?
Edited: Tue July 06, 2010 at 3:58 PM by mhamilton
Sorry no low pressure switch- on a variable compressor system---non-cycling system..... what you have is a high side pressure transducer (3 wire) - right next to upsidedown high side port- this transducer tells ecm whn to disable a/c for low pressure, high pressure, and when to turn on fan(s). To charge system- simply fill into a vacuum and then turn a/c on- once transducer sees 47 psi a/c compressor is enabled. Do NOT try to jumper a 3 wire transducer- ecm damage can occur.....if you insist on jumping compressor- do it at a/c relay in underhood electrical center...
Common leak points are compressor shaft seal and body o-rings-- all rebuildable.....
The number one A/C diagnostic tool there is- is to know how much refrigerant is in the system- this can only be done by recovering and weighing the refrigerant!!
Just a thought.... 65% of A/C failures in my 3200 car diagnostic database (GM vehicles) are due to loss of refrigerant due to a leak......
Thanks! I was wondering if it wasn't a variable compressor after I didn't find a LP switch, didn't look too closely at it though. Wasn't going to jump the pressure switch, was just looking for the leaks. Had a few LP switches leak on other GM cars, figured it was just hidden under the fender somewhere.
I'll pull a vacuum and see if it will hold.
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