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  1. #1
    Join Date
    Jul 2010
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    Denver, CO
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    single phase compressor short

    I have a Carrier ductless split system thats a little over a year old. The compressor failed shorting to ground. I have continuity on all three legs to ground which says to me the common is shorted. I believe that the reason is an under voltage situation caused the failure but I want to know other circumstances that cause a short to ground. Tell me your knowledge on whay causes these shorts.

  2. #2
    Join Date
    Apr 2012
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    Paper Street Soap Company
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    Its an inverter right ? Variable frequency and voltage.

    If the unit saw low voltage it would most likely cause an inverter alarm

    It might be manufacture defect

  3. #3
    Join Date
    Nov 2004
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    up in the hizzy
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    1,407
    Quote Originally Posted by HuNGRYTeCH View Post
    I have a Carrier ductless split system thats a little over a year old. The compressor failed shorting to ground. I have continuity on all three legs to ground which says to me the common is shorted. I believe that the reason is an under voltage situation caused the failure but I want to know other circumstances that cause a short to ground. Tell me your knowledge on whay causes these shorts.
    loss of oil, overcharge,flooding. is the evap located lower or higher than the condenser? how long is the line set?

  4. #4
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    Jul 2010
    Location
    Denver, CO
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    435
    It is not an inverter, Carrier just uses a scroll with and accumulator on the 3 ton mini split.
    The evap is about 15 feet higher than the condenser and the run is about 140', which I realize is long but I do not believe that oil migration is the cause here, though i could be wrong. I find it hard that the compressor could slug due to the accumulator and the outside air temp not dropping below 70 over the last week with highs over 100. I am leaning towards power issues...

  5. #5
    Join Date
    May 2003
    Location
    Utah
    Posts
    735
    Compressor manufacturers will tell you that a high percentage of compressors returned for warranty where the failure was motor burn are the result of some mechanical failure that then led to the motor failure.

    There is some frequency of motor failures due to voltage imbalance issues at the compressor, due to loose power wires, worn contractors, etc.

    It's pretty rare to have a defective motor.

  6. #6
    Join Date
    Sep 2008
    Location
    Cedar Rapids, IA
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    487
    Quote Originally Posted by HuNGRYTeCH View Post
    I have a Carrier ductless split system thats a little over a year old. The compressor failed shorting to ground. I have continuity on all three legs to ground which says to me the common is shorted. I believe that the reason is an under voltage situation caused the failure but I want to know other circumstances that cause a short to ground. Tell me your knowledge on whay causes these shorts.
    Power surge / lightning most likely.

  7. #7
    Join Date
    Aug 2010
    Posts
    3,496
    The winding is all connected, so there's no telling which part is shorted with a multimeter.

    It's like hunting down where exactly the thermostat cable is shorting.

    bunny, TS said single phase, so there's no such thing as voltage imbalance.


    The winding does not touch the core directly, so something must have caused it to break the wire and touch the core, which comes down to mechanical failure which causes subsequent motor damage.

    I want to see what happened. You should cut it apart and take pictures.

  8. #8
    Join Date
    Jul 2010
    Location
    Denver, CO
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    435
    Quote Originally Posted by ICanHas View Post
    I want to see what happened. You should cut it apart and take pictures.
    I would love to but this one goes back to Carrier as warranty. I have about 40 compressors in the shop from this summer so maybe I'll go through them and find one shorted to ground, if I ever get some free time that is.

  9. #9
    Join Date
    Sep 2008
    Location
    Cedar Rapids, IA
    Posts
    487
    Quote Originally Posted by HuNGRYTeCH View Post
    I would love to but this one goes back to Carrier as warranty. I have about 40 compressors in the shop from this summer so maybe I'll go through them and find one shorted to ground, if I ever get some free time that is.
    Most compressor manufacturers cut open a number of their warranty returns to perform an inspection to determine the cause of the failure. You can usually request that they inspect your unit and let you know what they found. No guarantee that they will comply, but I have had good luck getting reports on units in the past.

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