7.5 ton straight cool 3 phase compressor failure?
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  1. #1

    7.5 ton straight cool 3 phase compressor failure?

    I think I have this right but want to check before I replace the entire condenser. It ran for two days clicking in and out from a bad contactor before I was told. Once I replaced that part and let it cool down since it was in thermal overload it started but no cooling. First I check the plate for amps and it says LRA 25. All three phases are at about 18. I shut everything down ( I don't want it to get hot again) and hook up my gauges. In static I am getting about 150 on the high (R22) and pegged on the low. Start up the unit and the gauges don't move and the amps do not increase but the compressor is getting hotter. It seems cut and dried the valves in the compressor are shot but I was hoping for a comfirmation before I purchase a new condenser. This part doesn't matter but it is a 1995 Bryant with a copeland compressor. Thanks a lot.

  2. #2
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    Are you a technician or intrepid DIYer ???

    If you're a tech what do you mean by the suction was "pegged" ?

    And 18 amps doesn't sound like bad valves

  3. #3
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    Copeland recip, or scroll?
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  4. #4
    Quote Originally Posted by Six View Post
    Are you a technician or intrepid DIYer ???

    If you're a tech what do you mean by the suction was "pegged" ?

    And 18 amps doesn't sound like bad valves
    Pegged means it was pegged or maxxed to the highest reading on the gauge which was 150. So both high and low read 150 with the unit off and do not change with the unit running. The amp draw stays the same on all three legs but the compressor tempeture goes higher. Process of elimination makes it seem like the compressor since if it had a restriction the pressure would go up or the amp draw would rise. I guess the valves becuase basically ''nothing'' seems to be happening with the compressor running. Thanks

  5. #5
    Quote Originally Posted by beenthere View Post
    Copeland recip, or scroll?
    Recip

  6. #6
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    Guessing you meant RLA 25 and not LRA. 18 amps would indicate that its either pumping, or has a bearing that is tight along with bad valves. Which would point to a problem else where in the system having caused the problem with the compressor.

    I would make sure that my hoses where depressing the cores the whole way before I condemned that compressor for bad valves.A non pumping compressor generally has a low amp draw.
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  7. #7
    Quote Originally Posted by beenthere View Post
    Guessing you meant RLA 25 and not LRA. 18 amps would indicate that its either pumping, or has a bearing that is tight along with bad valves. Which would point to a problem else where in the system having caused the problem with the compressor.

    I would make sure that my hoses where depressing the cores the whole way before I condemned that compressor for bad valves.A non pumping compressor generally has a low amp draw.
    The tag says 25 amp and it is only pulling 18, so this is low???

  8. #8
    I don't have a schrader on the low side, once I hook up I have to turn in the valve. I see what you are saying about a bad bearing as well.

  9. #9
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    Compressors very seldom pull RLA. Its pulling 72%, which is ok.
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