a/c issue not seen before

Discussion in 'Heavy Duty Diesel Truck Mechanics Forum' started by jazzedman, Feb 15, 2019.

  1. jazzedman

    jazzedman Bobtail Member

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    Got a 2000 Sterling in the shop, a/c had leaked out, pressurized system and found two leaks. Fixed both, found some metal in the orifice tube so replaced compressor (along w/oriface tube and accumulator) and flushed system. charged system. compressor kicks in, gets nice and cold (34*) but the compressor does not cycle and the low side is in retard. wondering what my issue is. checked evaporator for fins being plugged with ####, its clear. anybody come across this?
     
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  3. jazzedman

    jazzedman Bobtail Member

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    low side is so high it's in ReTaRd.
     
  4. RET423

    RET423 Medium Load Member

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    If the low side is high and the compressor does not kick off then the pressure switch is not working, it should kick off the compressor if the pressure gets too low or too high; sometimes there are separate switches for high and low and sometimes one switch handles it all.
     
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  5. RustyBolt

    RustyBolt Road Train Member

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    Pressure switches are generally pretty cheap. If I'm replacing a compressor, etc. they get changed too.
     
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  6. Rideandrepair

    Rideandrepair Road Train Member

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    Yep high pressure switch.
     
  7. jazzedman

    jazzedman Bobtail Member

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    The first leak i found was the high pressure switch leaking through one of the pins. So it was changed with everything else. Did not change the low pressure switch.

    So maybe my low pressure switch is bad then? Will try that first thing Monday morning.
     
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  8. Rideandrepair

    Rideandrepair Road Train Member

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    If compressors working low pressure switch should be good. On mine I can unplug high pressure switch and the compressor shuts off.A break in the wire to switch can cause a lot of confusion, replacing switches. I have a few spares. Lol I would suspect a plugged orifice, or expansion valve if you had one. Condenser and evaporators are nearly impossible to flush completely. Trash finds it’s way back and eventually eats up compressor.In line filters are available, an option to keep from going through compressors.
     
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