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Thread: AC high pressure switch replacement

  1. #1
    Junior Member
    Join Date
    May 2018
    Calgary, Alberta
    1993 Cutlass Ciera 3.3

    Default AC high pressure switch replacement

    I was diagnosing an inoperable rad fan on my 1993 Ciera 3.3 and the diagnostic chart I found online got me to test the AC pressure switches first. What I did was: took connector off of low pressure switch and installed a jumper, to no avail. Then i went underneath to the high pressure switch on the back of the compressor, took off the pigtail and put a jumper on it. Then I went back to the low pressure switch connector, put in the jumper, and lo and behold the compressor locked up, and the rad fan come on. I then took the jumper off of the low pressure connector, put it back on the switch, and retried the system. The compressor came on like normal. At that point I determined that the high pressure switch was faulty.

    My question is: how hard is it and what do I have to do to replace the high pressure switch while the compressor is still installed on the vehicle? Do I have to get the refrigerant evacuated before changing the switch?

  2. #2
    Senior Member
    Join Date
    Oct 2007
    West Jefferson, OH


    If the pressure switch is compressor mounted, then yes, the system needs evacuated. Then you remove the internal type snap ring and pull out the switch. If the system is in a vacuum from having the refrigerant removed, it might not come out very easy. Once it's out, you will replace the o-ring (should come with the new switch, along with a snap ring) and put a little A/C oil on it as a lubricant. Then install the new switch.

    '86 Eurosport VR coupe
    '86 Eurosport sedan
    '88 Eurosport VR coupe
    '89 Eurosport wagon

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