1990 Volvo whitegmc "WCA?" help/wiring, 855 cu Cummins

Discussion in 'Heavy Duty Diesel Truck Mechanics Forum' started by bwebster, Sep 23, 2018.

  1. bwebster

    bwebster Bobtail Member

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    Sep 23, 2018
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    Needing help/info on new/used truck to the farm operation. It's a 1990 Volvo/Whitegmc I think it is a WCA. 855 cu Cummins.
    It has some rigging and work around from years past that I need to remove. One is a jumper to keep the cooling fan activated constantly. Makes for some horrible mpg's and keeps the a/c compressor on regardless of switch position.
    Tracing wires is proving quit difficult/tedious.

    I'm in real need of a manual or minimum a wiring diagram. Can/will anyone help?
     
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  3. bwebster

    bwebster Bobtail Member

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    Sep 23, 2018
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    Not a soul knows anything about a 1990 Volvo White/GM truck?
     
  4. 062

    062 Road Train Member

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  5. BoxCarKidd

    BoxCarKidd Road Train Member

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    I worked on a lot of them. All of my manuals are for Detroits. If you can post pictures of your fan clutch and sensors on your water rail one of us maybe able to walk you through it.
    A/C wiring is likely the same. PM me an Email and I will try to get it to you.
     
    062 Thanks this.
  6. BoxCarKidd

    BoxCarKidd Road Train Member

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    KIMG1179.jpeg KIMG1177.jpeg Can't send pictures? Not a soul you know can? It would just be easier and more likely correct.
    They often are set up like this. Has a push button switch for the A/C compressor. Power wire from that goes to the thermostat. It is located behind the passenger side kick panel in front of the door hinge. Power goes from that to the trinary switch on the dryer.
    The trinary switch has four terminals. Two beside each other power the compressor from the thermostat. It is also the low pressure switch and can cut out the compressor. The other two control the engine fan. One I thank is hot all the time with the key on. The other goes to the fan solenoid, could be via the engine temp fan control switch. New switches have the wiring diagram on them and some souls can find it on line. Low pressure cut out happens at about 18-22 PSI and high pressure cuts the fan on at about 275-325 PSI.
    The engine temperature fan control switch will be screwed in the water rail behind the thermostat. It should have power to it any time the key is on. Is closes the circuit and sends power to the fan air solenoid at about 210 degrees. Its temp setting should be stamped on it.
    All off the top of my head and open for corrections but I thank that is what he has. Not many of them View attachment 249260 left here and they are not good examples as they have been cobbled, I mean altered.
     

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