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  1. #1

    semi hermetic compressor problem

    walk in freezer, 404a, one of the outside fan motor was seized, i replaced it.fan motor started working but comp.wasnt starting, found start cap was out. replaced it, now it would start and pull 98 amps and shuts down also trips the oil pressure switch. i thought comp. was locked. told cutomer he needs new comp. cutomer called another tech and he got the semi hermetic comp. going. what i heard from customer is he shut the valve off and then let the refrigerant let in slowly. please let me know what the other tech. did in detail. i am new to refrigeration.

  2. #2
    Join Date
    Oct 2011
    Location
    Chicagoland Area
    Posts
    4,750
    A single phase unit with an oil safety? That's a new one on me. The tech throttled the refrigerant in using the service valves to get the oil out of the evaporator and back to the compressor.
    Officially, Down for the count

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  3. #3
    Join Date
    Mar 2011
    Location
    North Carolina Piedmont Area
    Posts
    451
    Sound like the compressor was under a full load at start up. By closing the suction line and limiting the supply of refrigerant to the compressor, will decrease LRA. It is possible that closing the valve off entirely was necessary so that a pump down effect could take place. It may have been necessary to to this pump out procedure a few times until finally opening the suction valve slowing until RLA was acceptable so as not to trip circuit breaker.

    What was the HP for the compressor and was it a hermertic, semi, or scroll?
    Did it have a receiver or not.

    What was LRA rated at and was the power arrangement set up correctly?

  4. #4
    Join Date
    Dec 2008
    Location
    Nor•Cal
    Posts
    221
    Does suction line have a crankcase pressure regulator? Not common on walk-ins, but I have seen them.

    But yeah, sounds like the other tech front seated the suction service valve, then opened it gradually to keep compressor from overloading from excessive suction pressure.

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