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  1. #1

    Default 1999 C2500 A/C clutch doesn't disengage

    I just changed the compressor, accumulator and dryer and recharged the system. Also, just had the air inlet actuator replaced. I noticed the compressor (clutch) never stops spinning, regardless of what fan speed and/or how cold it may be in the cab. Could the culprit be the switch that is located on the accumulator? I've heard it is called the low psi switch, and/or, the clutch cycling switch. Any assistance would be appreciated. TIA James

  2. #2


    Well, replacing the switch located on the accumulator doesn't seem to cycle the compressor clutch. Maybe if i begin from the day i purchased the truck, this might help diagnosing the problem. I bought the truck about 5 weeks ago (early June). During a trip, the vents began blowing warm air and we noticed condensation forming on the blower housing and water beginning to drip on the passenger floor mat; I assumed the evaporator was icing up, and/or, the drain tube (out of fire wall) may be plugged. turning the AC knob on and off the entire trip was necessary to stay somewhat cool. The next day (after a 300 mile trip) took truck to a mechanic and he said the compressor was shot. Went to O'reillys and bought a new (not used) Murray compressor, accumulator and orifice tube. Mechanic installed it and drove it and said it was working satisfactory, but, did tell me the re-circulation door wasn't operating and that it could be in the control head. I told him i would look into it.

    We drove home a couple of days later and the truck was cooling much better. However, there was still condensation on the blower housing and puddling on the floormat. I assumed this was because the system was trying to cool incoming 95degree air and not cabin air, or, there was still some pluggage. Fast forward to last week, i had the actuator replaced on the air inlet door. Definitely could tell the difference while driving around in town, and, i never noticed any condensation develop on the blower housing. I figured the problem was fixed.

    Last Wednesday, we made the same 300 mile trip to visit my wife's parents. Everything seemed fine, but, close to our destination, i noticed the passenger floor mat was a little wet. I also noticed the condensation again on the blower housing. The next morning, i popped the hood, started truck and turned the AC on, cranked on high. Within a 20 minute span, i realized the clutch never cycled off; it just stayed spinning. Still not knowing exactly what this switch did or was called, i replaced it with one from NAPA. This still did not allow the compressor clutch to cycle.

    On the way home this past Saturday, the AC ran fine; however, there was still condensation around the blower housing and some dampness on the floor mat. With what i've just posted, does anyone have any ideas what i should check for next?? I'm short on funds and don't really want to take it to a mechanic unless i absolutely have to. Any help at all would be greatly appreciated. thanks, James
    1999 Chevy LS Crewcab 2WD (OBS)
    5.7, 4L80E, GT4/G80

  3. #3


    Sorry, I didn't see this thread when I answered your question in an other thread ( ). I must confess, I did not read all of the info on your 2nd post, so my answer may be wrong. but, check the relay anyway.

    '09 Avalanche LTZ - Black
    '05 Envoy XL (sold)

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