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  1. #1
    Join Date
    Oct 2008
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    742

    Another bad compressor...

    Just info.

    Had a True T23F tripping a breaker. Isolated down to the condenser. Ohmed comp windings as good. No issues there. Megger tests to compressor case was good too.

    With condenser practically in my lap, using an extension cord and an in-line GFCI as aux power source, I'd plug in condenser. The compressor would do an abbreviated startup kick along with the sound of something from the compressor's vicinity akin to the nearly imperceptible noise of dropping a tennis ball on carpet from say...a foot high.

    I ordered and replaced the start components. SAME RESULT!

    Retested compressor. Same readings. Compressor WASN'T testing as shorted.

    Disconnected compressor terminals. Applied power. Carefully touched line input to C terminal. Tennisball noise and GFCI tripped.

    Now I have no faith in my megger.


    "You never know what others don't know." -

    If I can't laugh at myself...then I'll laugh at YOU! -

  2. #2
    Join Date
    Jan 2010
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    6,239
    With all the electrical test instruments i would say you got that covered. Now if they could come up with some mechanical test instruments that would be great.

  3. #3
    Join Date
    Aug 2006
    Location
    st.petersburg,fl
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    803

    Lightbulb

    Take it off the GFI. They do not work well with them, and will eat compressors. When a store calls me and says they have a reach in and they have to keep reseting breaker first thing I tell them is to install standard breaker or receptical .... And just like magic the problem goes away...


    Dedicated circuits and no GFI helps maks happy R/I


    Hope this Helps
    Isn't sanity just a one-trick pony anyway? I mean, all you get is that one trick, rational thinking, but when you're good and crazy, well, the sky's the limit!

  4. #4
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    Aug 2006
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    st.petersburg,fl
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    803

    Lightbulb

    One more item I forgot to mention is thet use of GFI could Void your manufactures warranty...
    Isn't sanity just a one-trick pony anyway? I mean, all you get is that one trick, rational thinking, but when you're good and crazy, well, the sky's the limit!

  5. #5
    Join Date
    Jul 2009
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    Quote Originally Posted by skpkey9 View Post
    Take it off the GFI. They do not work well with them, and will eat compressors. When a store calls me and says they have a reach in and they have to keep reseting breaker first thing I tell them is to install standard breaker or receptical .... And just like magic the problem goes away...


    Dedicated circuits and no GFI helps maks happy R/I


    Hope this Helps
    So true...I have seen that problem more often now as electrical codes have changed. Seems like everything has to be GFCI in newer stores!

  6. #6
    Join Date
    Oct 2008
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    742
    Quote Originally Posted by skpkey9 View Post
    Take it off the GFI. They do not work well with them, and will eat compressors. When a store calls me and says they have a reach in and they have to keep reseting breaker first thing I tell them is to install standard breaker or receptical .... And just like magic the problem goes away...


    Dedicated circuits and no GFI helps maks happy R/I


    Hope this Helps
    Actually I hate the things. Never heard voiding a warranty but many manufacturers won't cover the expense of the service call for just that problem.
    I too have told many a store manager to go to a conventional outlet. Every manufacturer I've queried tell me their product wasn't designed to run from a GFCI. I never asked why because it's obvious - INSIDE the box there's electrical controls, fans and...MOISTURE.

    Actually the GFCI I referred to was an in-line I use RARELY (company provided). For this occasion it was saving me a rather rigorous trek back & forth to the mechanical room where the breaker was located. That final test DID trip the breaker anyway - despite the GFCI.


    "You never know what others don't know." -

    If I can't laugh at myself...then I'll laugh at YOU! -

  7. #7
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    Did you isolate the compressor from the condesor fan when checking this?

  8. #8
    Join Date
    Oct 2008
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    Quote Originally Posted by pdrake65 View Post
    Did you isolate the compressor from the condesor fan when checking this?
    Gotcha. Well, I spent entirely too much time on this whole problem, including changing out that motor because I was getting ground readings from it - I think. Did I isolate it? Don't remember. I know very well when and why to isolate, and do so as a rule.

    The concluding moment was:
    1. With compressor COMPLETELY disconnected from the circuit
    2. Applied power to the condensing unit via my extension cord. So far, so good.
    3. Took that disconnected wire that goes to C terminal and touched it to compressor's intended terminal.
    4. A little spark and my GFCI trips. Remember, R & S aren't connected. It's an open circuit.

    As such, the compressor has some internal ground my megger wouldn't find (1000v) but line power does (115v).

    As straight forward that isolating down to ground short should be, sometimes I run myself through the wringer...disconnecting stuff to isolate, drawing my own little diagram to remember how they reconnect. Heck, this freezer should've simple compared to some of the over-designed cooking equipment I've tangled with.

    Of course, when I get back there with the new compressor I've ordered (an Aspera compressor), I'll check it AGAIN for the umpteenth time to be sure I didn't miss something. I go to great efforts to prove a compressor is bad before changing it.

    I still have bruises on my head from the wall there...


    "You never know what others don't know." -

    If I can't laugh at myself...then I'll laugh at YOU! -

  9. #9
    Join Date
    Aug 2006
    Location
    st.petersburg,fl
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    803

    Lightbulb

    ECtofix : well its kind of like this...
    say you have a customer that you just changed a compressor on their system and you found out the reason was that they used an extension cord ( undersized wire ) and loss of compressor was do to voltage drop... now you explained tp them why they could not use an extension cord...couple of days pass and they call back saying unit isn't cooling, you arrive to find the same extension cord hooked up and they want it changed under warranty.... same with manufactures they say dedicated circuit with no GFI....and I have been asked before.
    Isn't sanity just a one-trick pony anyway? I mean, all you get is that one trick, rational thinking, but when you're good and crazy, well, the sky's the limit!

  10. #10
    Join Date
    Jan 2010
    Posts
    6,239
    Try the reverse trick. What do you have to lose ?

  11. #11
    Join Date
    Aug 2006
    Location
    st.petersburg,fl
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    803
    rev only works on 3 phase....single phase use larger start cap.

    This compressor is toast just replace compressor have GFI changed and off to the next nightmare you go...
    Isn't sanity just a one-trick pony anyway? I mean, all you get is that one trick, rational thinking, but when you're good and crazy, well, the sky's the limit!

  12. #12
    Join Date
    Aug 2006
    Location
    st.petersburg,fl
    Posts
    803

    Lightbulb

    and when I say use a larger start cap its to bump a locked compressor then go back to proper sized one...
    Isn't sanity just a one-trick pony anyway? I mean, all you get is that one trick, rational thinking, but when you're good and crazy, well, the sky's the limit!

  13. #13
    Join Date
    Jan 2010
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    6,239
    Quote Originally Posted by skpkey9 View Post
    and when I say use a larger start cap its to bump a locked compressor then go back to proper sized one...

    Skpkey,
    There's another thread going about reversing single phase. Basically reversing the start and run windings.

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