Casey Posted October 1, 2007 Report Share Posted October 1, 2007 '96 Cutlass Supreme w/150k miles on the odo... After reading old posts and the FSM, directly powering the A/C compressor with hot battery power (sounded like clutch movement), and not finding any fuses nor relays obviously blown, I'm guessing the problem is low pressure in the A/C lines. Is there a way to by-pass/jump the low pressure switch: ...in the line from the condensor to the evaporator to get the A/C clutch (and cooling fans) to engage and come on? I see a red/black tracer, black and gray wires in the switch's connector. A/C was never working and I've only had the car for three weeks, so no real history to go on. Quote Link to comment Share on other sites More sharing options...
slick Posted October 1, 2007 Report Share Posted October 1, 2007 Only 1 fan is controlled by the AC. The other turns on at a specified temperature, via the ECM. Check your fuses and relay's. Is your AC system just low on refrigerant? Quote Link to comment Share on other sites More sharing options...
Casey Posted October 1, 2007 Author Report Share Posted October 1, 2007 Only 1 fan is controlled by the AC. The other turns on at a specified temperature, via the ECM. Check your fuses and relay's. Which one? I did check all of the fuses and checked the #1 and #2 fan control relays. Is your AC system just low on refrigerant? I have no idea if it is or isn't low. The FSM states the PCM controls the A/C clutch and turns it off if the pressure is too low and controls the cooling fan operation. Seems to me that'd be a huge coincidence that both stopped working and weren't directly related. Would I be better off just plunking down the $30 for an R-134A recharge kit at this point and seeing what happens? Quote Link to comment Share on other sites More sharing options...
Casey Posted October 7, 2007 Author Report Share Posted October 7, 2007 I just re-filled the A/C refrigerant to the correct level and pressure range, and there's no change. Still no A/C clutch engagement and no #2 electric cooling fan engagement. I did verify both fan relays and the A/C realay at UH center #1 are all good, and the drivers side fan (#1) came on when the temp got up to about 3/4 on the temp gauge, so I know that fan is working. How common is it for the high-pressure switch to fail? FSM states it cannot be repaired, but rather must be replaced. I jumped the switch terminal's red and grey wires, and both fans engaged (#1 and #2), so at least the wiring to fan #2 is good. This leads me to believe the high-pressure switch is shot and needs to be replaced, since it works just fine when by-passed and the low-pressure side has approx. 45 psi in the line, which is where it should be. Comments/suggestions? Will the all of the A/C refrigerant need to be re-claimed and re-filled when/if the switch is replaced? I'm guessing so, since I doubt there a one-way valve where the pressure switch threads into the ref. line... Quote Link to comment Share on other sites More sharing options...
LuminaPower92 Posted June 11, 2008 Report Share Posted June 11, 2008 I know its been a bit since this topic but wondering if you found the problem? Sounds exactly whats going on with my Z and was wondering about the switch as well, one tech told me there was a valve there and you didnt need to evac it, but replace it, but who knows. Just curious if you fixed it and found what was causing this. Quote Link to comment Share on other sites More sharing options...
intern8tion9l Posted June 12, 2008 Report Share Posted June 12, 2008 my a/c hasn't worked for like 3 years.....system is full, brand new condenser. ever since the motor swap my compressor clutch won't engage. and it's been in the 90s.....needless to say i'm pissed Quote Link to comment Share on other sites More sharing options...
89SupremeCutty Posted June 12, 2008 Report Share Posted June 12, 2008 if the compressor isn't coming on or engaging, how could you have put refrigerant in it? if you have the 3100, try using a jumper wire in place of the a/c relay. unless you have already done that. Quote Link to comment Share on other sites More sharing options...
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