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  1. #1

    Grounded compressor

    First post here. 6 year installer 1 year tech currently enrolled in a 2 year HVAC program at a West GA Tech. NATE certified ID # 1997427.

    I had a no-heat call the other day on a Lennox HP. The breaker would trip just about as soon as the unit would try to run. Compressor LRA is 85 and read 83amps at startup until of course the breaker tripped. Recip compressor btw and capacitor was in good shape showing proper MFD. Next thought was to check the windings on the compressor. What got me was that each had a reading to ground. Run, start, and common. Diagnosed as grounded compressor heh. But is this common as everyone I seem to have asked has never seen it but it seems totally possible.

  2. #2
    Join Date
    Apr 2008
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    Pluto
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    No one you work with has ever seen a grounded compressor? Yeah, right. See them all the time.
    Not as lean, not as mean, but I'm still a hardcore, ass-kicking, hard charging Marine! Oohrah!

  3. #3
    Well what i meant was its common to see one winding grounded. What was strange was that all three of them showed a reading to ground.

  4. #4
    Join Date
    Jan 2010
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    over here
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    Sounds like you answered it.........

  5. #5
    Join Date
    Feb 2009
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    Tallahassee, FL
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    3 windings?

  6. #6
    Join Date
    Jun 2002
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    Quote Originally Posted by amasuperbike View Post
    3 windings?

    This thread belongs in the Professional technical forum.
    Last edited by glennac; 01-23-2010 at 12:24 PM.
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  7. #7
    Join Date
    Jan 2004
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    Lancaster PA
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    It can happen.

    Its not actually 3 windings in a single phase compressor.
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  8. #8
    Join Date
    Feb 2009
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    Tallahassee, FL
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    Thats what I wanted him to question and then understand. There is only 2 windings in a single phase compressor. You have to picture that there are two motors in that shell and they are tied together at L1. So its very common to find them grounded at all terminals. Very Common. You will see plenty.

    Shorted compressors are sometimes hard to diagnose with your meter. They throw the breaker as soon as its reset. The best way I have found to be certain its nothing else is disconnect common from the comp terminal without touching anything else. If it resets than it the comp for sure.

  9. #9
    Join Date
    Jan 2004
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    I think a lot of people get screwed up because a 3 phase has 3 terminals. And they just associate 3 windings with 3 terminal post.
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  10. #10
    Join Date
    Feb 2009
    Location
    Tallahassee, FL
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    Absolutely. Just remember if has a run cap its not three phase. And dont get confused and mistake a fan mtr run cap for the comp.

  11. #11
    Join Date
    Nov 2006
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    Southeastern Pa
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    18,260
    ...and remember to


    [edit]

    I just caught myself posting something that could be DIY.

    Get your count up and apply for pro membership.

    See you in the Technical forum.
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  12. #12
    Join Date
    Jun 2004
    Location
    Howell, Michigan
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    16,176
    Moved to Pro

  13. #13
    Join Date
    Jun 2004
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    Ok, I moved this to pro and cleaned it up, moved back to residential.

    To the original poster, threads like this are better off in the Professional Forums, get your 15 posts and apply for pro membership.

    Thread closed.

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