No a/c

Discussion in 'Ask An Owner Operator' started by Giddy-up13, Jul 21, 2021.

  1. Giddy-up13

    Giddy-up13 Bobtail Member

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    Jul 21, 2021
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    99 KW T-600. Replaced entire “heater box” as complete unit. Now compressor clutch will not engage. Ideas?
     
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  3. kwswan

    kwswan Road Train Member

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    Check fuses & relays.
     
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  4. reeferwrencher

    reeferwrencher Medium Load Member

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    Is the compressor/clutch new?
     
  5. Giddy-up13

    Giddy-up13 Bobtail Member

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    Jul 21, 2021
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    New last year. It engages when using jumper wire.
     
  6. Dale thompson

    Dale thompson Road Train Member

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    Low on Freon or a bad trinary switch.
     
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  7. abyliks

    abyliks Road Train Member

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    Did you put guages on it?
     
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  8. w9l

    w9l Medium Load Member

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    Test your high and low pressure switches. If I am thinking right the high switch will be somewhere in a line on the metal part upfront around compressor line connection or condenser line connection and will have a weatherpak plug with 2 wires unplug it from the round switch and jump the female terminals in the plug with a paperclip. Low pressure will look neatly the same but back around firewall . If it starts with either one put gauge set on and go from there. Actually be good to have gauge set hooked up when testing.
     
  9. w9l

    w9l Medium Load Member

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    Come to think of it.... have you already evacuated and recharged system with proper amount of 134a? If you are trying to charge it and compressor won't kick in and let system draw freon, either jump low pressure switch or I usually just run a hot wire to compressor and force clutch to engage while I add another can or two then hook wires back up so that compressor can cycle properly and finish charging. My older KW I have to do this anytime I start from 0 freon. My newer one- so far- will go ahead and short cycle after putting a couple of cans in while in a vac or low psi.
     
  10. truckdriver31

    truckdriver31 Road Train Member

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    they never do. lol
     
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  11. Ridgeline

    Ridgeline Road Train Member

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    What’s a gauge?
     
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