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Thread: Mcquay PTAC

  1. #1
    Join Date
    May 2011
    Location
    NEPA
    Posts
    12

    Mcquay PTAC

    Mcquay PTAC: compressor runs for a while, seems to be cooling, then compressor shuts off and digital display starts flashing "LA." Could it be a Thermistor problem? Charge may also be slightly low as only the bottom 1/3 of the evaporator seems to be sweating. (85* ambient and very high humidity at test bench)

  2. #2
    Join Date
    Jun 2004
    Location
    Olean, NY
    Posts
    1,449
    mod#?
    Guinness for strength

  3. #3

    ptac

    wat kind of ptac do u have

  4. #4
    Join Date
    May 2011
    Location
    NEPA
    Posts
    12
    It is a model PDAA. The evaporator and condenser were both filthy, I cleaned them both with Nu-Brite and bench tested it. It ran, but I was only getting 13* delta T across the evap. That is setting on the bench, no shroud, just running in my shop. (93* ambient) Tomorrow I'm gonna install it in one of the empty apartment rooms and test it under a more controlled situation.

  5. #5
    Join Date
    May 2011
    Location
    NEPA
    Posts
    12
    Ran unit all day long in an empty aptmt. Ran fine, kept room at 72* with compressor cycling on and off, but suction pressure (R-22) is 85PSIG! That is factory charge, no one has added any refrigerant to the system. Still only getting 10*-12* delta T across evap.

  6. #6
    TXV or Constant Pressure Expansion Valve?

    --Paper Road

  7. #7
    Join Date
    May 2011
    Location
    NEPA
    Posts
    12
    neither, it has a cap tube.

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