A\C issue????

Discussion in 'Trucks [ Eighteen Wheelers ]' started by bigfletch, Jun 11, 2013.

  1. bigfletch

    bigfletch Bobtail Member

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    Dec 25, 2011
    henderson, tx
    0
    Got a 99 Pete. Replaced orifice tube, compressor, dryer, and expansion valve. Also sucked all old fluid out of system. My problem is the ac will blow cold for a little while then compressor will shut off. The only way it will stay blowing cold is if I run the engine fan. Any suggestions????
     
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  3. brenes-built

    brenes-built Light Load Member

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    Apr 14, 2011
    Vancouver, Wa
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    It's probably your high pressure switch. Usually on the driver side of the radiator on a A/C line.. I'm not 100% sure that's the one because there is another one by the firewall.
     
  4. bigfletch

    bigfletch Bobtail Member

    18
    1
    Dec 25, 2011
    henderson, tx
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    Ok thanks. I'll check it out
     
  5. BullDoggin

    BullDoggin Light Load Member

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    Jan 27, 2013
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    It has an expansion valve AND an orifice tube?
     
  6. bigfletch

    bigfletch Bobtail Member

    18
    1
    Dec 25, 2011
    henderson, tx
    0
    Yes the expansion valve was under the sleeper, and the orifice tube was up front.
     
  7. mtoo

    mtoo Road Train Member

    1,936
    4,514
    Jan 15, 2011
    Retired on bended knee
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    One time I was working on mine and cut an o ring as I was putting it together. It was leaking out almost as fast as I was putting it in. So double check your connections.
     
  8. beltrans

    beltrans Medium Load Member

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    Nov 26, 2008
    spokane wa
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    Could be overcharged.....
     
  9. BrianE

    BrianE Light Load Member

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    Mar 9, 2013
    Livingston Texas
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    That was my first thought. R134 systems are very touchy. You need the exact charge or they will not work right.
     
  10. Floyd

    Floyd Light Load Member

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    25
    Jun 1, 2010
    Central Maine
    0
    My first thought is that the condensor core fins might be plugged. A plugged condensor will create higher than normal pressure causing the compressor to cut-out via the high pressure switch. Constantly running the fan can compensate for this and lower the pressure enough to keep the compressor from cutting out.
    Try blowing the condensor core out with compressed air to see if this helps.......also while your there check to make sure your radiator, Air to air, and anything else up there is clear of debris/dust etc. Blockage in 1 of these could also be adding to the problem.
    If everything is clean and clear and it still doesn't work then i would verify that it isn't overcharged, and then check the high pressure switch. If you perform all of these things and it still doesn't work then there must be an internal blockage in the system.
    Good luck, and let us know how you make out.
     
  11. Ridgeline

    Ridgeline Road Train Member

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    Dec 18, 2011
    Michigan
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    The question I have is why did you replace all of that without flushing the system out completely?

    If you toasted a compressor, then there is junk in the system that needs to be cleaned out which means if it is bad enough, you will end up replacing the compressor soon.

    When you looked at the orifice tube, was there any debris in the screen?

    DO NOT use air to flush it, get it done right with a solution that will grab everything and take it all out.
     
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