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  • Manitowoc SD0422A zero pressure.

     olivero updated 1 month ago 3 Members · 3 Posts
  • tboling50

    June 15, 2021 at 8:52 pm

    Manitowoc SD0422a zero pressue on the low side. 120 high side. Compressor running but condenser fan is not. The unit is brand new but has sat for several years. Could it be a bad TXV?

  • fixbear

    June 16, 2021 at 8:03 am

    That or low charge.

  • olivero

    June 25, 2021 at 10:38 am

    Yup, either a TXV, fully clogged drier or low charge.

    Generally they'll run into a vacuum if they are low, or restricted either by dryer or faulty TXV.

    If I'm in doubt, I just add some refrigerant and watch the low side, if the low side stays low but the head goes up then it's not a leak, but a restriction. If the high side stays or only goes up slightly and the low side comes up, then it's a leak most likely.

    Usually does the trick.

    BUT if it IS a leak, and it IS 0 (or vacuum) then you probably have a moisture and non condensables in the system at which point, you might add refrigerant and the numbers get all wonky, so you could just try to pull whatever is left of the charge and weigh in new refrigerant and then see what happens, if the low side drops out immediately and high side shoots up, it's restricted

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