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A/C on a 91

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by dammit32, Aug 14, 2002.

  1. dammit32

    dammit32 1/2 ton status

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    bought this truck last fall ...it has a converted a/c system and looks like someone was using it ...but when i turn it on the fan works in the cab but the compressor doesnt kick in....at first impression i think-repace the pump- ....but there must be a EASY way to isolate the compressor and test it...the compressor doesnt look terribly old and they seem quite pricey for a replacement


    sweating in Maine /forums/images/icons/confused.gif
     
  2. Thunder

    Thunder 3/4 ton status

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    Here's a list of things that wont let the compressor start.
    First Be sure to check the fuse.
    Then check all the connections and wireing.
    If its ok
    Then start it up and turn on the AC put a volt meeter on the green wire that goes into the AC compressor it should be getting 12 volts. If it is getting 12 volts but not running the clutch coil is probabally bad.
    If its not getting 12 volts:
    It may be that some or all the refergerant has leaked out of the system. and the low pressure switch, sensing low pressure wont let the compressor start.
    To check it.
    look under the hood on the passenger side. you will see a silver can. This is the accumlitor/dryer. On top of the can is a plug with 2 wires going into it.This is the low pressure switch Disconnect the plug and jumper between the 2 wires. turn on the AC The compressor should start. If this starts the compressor dont run it long cause there may not be any lubricant going to it. The problem could be a bad low pressure switch or there is no refergerant in the system. To fix it you will have to find the leak fix it then recharge the system.
    Also when you pull that plug off the low pressure switch check to see if you are getting 12 volts with the AC on to one of the wires that goes into the switch.
    If the pressure switch isn't getting power the switch on the temp control pannel may be bad.
     
  3. Batchman

    Batchman Registered Member

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    Trun the AC on take the low-pressure cut-off switch off(spark plug looking thingy) the condenser and short it out with a paper clip the compressor should kick on means low on coolant charge your system.
     
  4. dammit32

    dammit32 1/2 ton status

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    i jumpered the low pressure switch and the compressor turned on so i tryed to recharge the system ....added two cans of 134a and now the compressor turns on intermittently ??? sometimes it stays on a while but must of the time just for a few seconds.... the compressor sounds slightly squeeky but it hasnt run for at least a year so i disregaurded it as a problem ....no cool air in the cab still.... /forums/images/icons/confused.gif
     
  5. PGL4VT

    PGL4VT Registered Member

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    You're still low on freon. Buy a guage. You can get one for under $10 from Advance auto. My AC had not worked in a year or more until July. It took 3+ cans to get it going. I added the ones with oil and all. Don't forget that. That may be why it's squeaking. Buy Freon with the oil and conditioner in it and add one more can. That should do it.
     
  6. Thunder

    Thunder 3/4 ton status

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    YES! Get the recharg kit with the guage and the can of R 134a + lubricant. Most auto parts stores and Wal-mart have them. Just adding refrigerant wont be enough. you need 8 oz of lube in the system to keep the compressor from blowing up. Also having the guage will tell you how much charge you have. R134 is not as forgiving as freon. Too high of a charge will blow the compressor. Your system will usually take around 40 oz to get it in the ball park of a good charge. with 134a it is better to be a little low than too high.
     
  7. dammit32

    dammit32 1/2 ton status

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    cool...I already added 2 w/the oit stuff in em ...i'll grab another
     

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