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  1. #1
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    Oct 2008
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    mid-Tennessee
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    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." -

  2. #2
    Join Date
    Jan 2010
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    6,065
    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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    802

    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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    st.petersburg,fl
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    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
    Location
    mid-Tennessee
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    684
    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." -

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

  8. #8
    Join Date
    Oct 2008
    Location
    mid-Tennessee
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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." -

  9. #9
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    Aug 2006
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    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
    Oct 2008
    Location
    mid-Tennessee
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    684
    Quote Originally Posted by skpkey9 View Post
    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.
    Man, if I'm looking for any possible solutions to a problem, this is the right place. That's why I come here.

    HOWEVER, it was MY extension cord. I was merely circumventing the inaccessibility the condenser's dedicated outlet built into the freezer. I'd already isolated the problem to the condenser, I was merely replacing thermostat's function by BEING the thermostat with my extension cord - for testing purposes only. Same thing applies regarding MY GFCI doohicky - which rests once again inside my toolbox.

    Quote Originally Posted by VTP99 View Post
    Try the reverse trick. What do you have to lose ?
    Compressor isn't locked up. It trips the breaker. Besides, I thought YOU were going to be the one to try that.

    Quote Originally Posted by VTP99 View Post
    Skpkey,
    There's another thread going about reversing single phase. Basically reversing the start and run windings.
    Actually, I'm the one who said that and ultimately hijacked that thread.

    SIDE NOTE: Logging in here on this forum makes me remember the days when my company's techs "reported in" each morning by gathering at the warehouse's picnic table. The discussions there were always educational, often funny and sometimes turned into a debate fed by a bunch of brainiac technicians. We got so much from those gatherings that we'd show up for work 30-45 minutes EARLY. Our launch time was 7:45; then we'd all jump into our vans to go off our separate ways to be someone's hero.
    One of the guys summed it up by saying he learned more in those minutes of our morning gatherings than he EVER could through the rest of his day.

    Now we all set off for our first calls from our homes. It's a rare treat to find two or more of us at the shop simultaneously.


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

  11. #11
    Join Date
    Jan 2010
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    6,065
    EC,
    Are you saying it starts then trips or trips instantly ? A locked rotor will trip the breaker this you know. I will try that trick but the opportunity is at hand for you now.

  12. #12
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    Aug 2006
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    st.petersburg,fl
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    ECtofix The extension cord thing was just an example to get you to understand why it could void a warranty thats all I was saying with that. its perfectly fine to do what you did everyone does it, but do you see where im coming from...
    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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    6,065
    Try the reverse trick. What do you have to lose ?

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