Ac compressor stuck on unless unplugged

Discussion in 'Peterbilt Forum' started by OFT2024, May 20, 2024.

  1. OFT2024

    OFT2024 Bobtail Member

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    Apr 23, 2024
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    05 379 c13

    noticed my ac wasn’t blowing good so suspected freeze up.

    was correct accumulator and lines froze (assumed evaporator as well)

    turned fan off ac switch off to thaw out yet compressor still ran which would exsplain freeze up had no blower motor running for hours yet compressor was running

    so unplugged compressor to prevent damage and clutch disengaged

    thoughts?
     
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  3. bad-luck

    bad-luck Road Train Member

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    High pressure switch bad or wrong one on the truck , or the same with low pressure switch.
     
    Last edited: May 20, 2024
  4. OFT2024

    OFT2024 Bobtail Member

    8
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    Apr 23, 2024
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    If the low pressure and high pressure is within operating range then the compressor would run, correct? So if a switch in theory stuck open you wouldn’t know unless u check pressures?

    I tested the relay port 30 and 86 has power so it’s telling it to be on just not sure why
     
  5. bad-luck

    bad-luck Road Train Member

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    I put on a high pressure switch from a friend that was for a peterbilt , which is what I own. It made my truck a/c freeze up. It can freeze up if the freon level is incorrect. A 379 takes 5lbs of freon, the only way to know how much is in the system is to have it drained and recharged.
     
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