Whats up with Run Capacitors on Goodman A/C units ???
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  1. #1
    Lately, i have been measuring voltage on the top of combo Run Capacitors that far exceed the voltage rating stamped on the Run Capacitor furnished with the Goodman A/C unit.

    IE: Todays measurement :
    Goodman 2 ton model CK24 unit . Rating of combo run capacitor : 370 v. Voltage as measured on top between common and Herm : 389 v. Unit was operating correctly and incoming voltage entering and leaving the Contactor was 245 v.

    Over the last few weeks, ive measured even greater variances on Goodman A/C Combo Run Capacitors between common and Herm as well as common and fan .How come they didnt put in 440 v. rated Combo Run Capacitors ?? Ive also had quite a few Combo Run Capacitors blow over the last few years on Goodman ... most likely due to the higher voltage imposed on them , than what the rating is.

    Anyone else running into this ?

    Dave

  2. #2
    Join Date
    Jun 2001
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    3,909
    Anyone else running into this ? Yes

    I usually go ahead and grab a 35/5 440 off of the truck.

  3. #3
    How can a Manufacturer not pick this up in their R&D ??

    RoboTec..if youre still with Goodman, whats your take on this problem ???

  4. #4
    Join Date
    Sep 2001
    Location
    angola indiana
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    528

    run caps

    I too have replaced many,many run caps on goodman condensers. I always repcace with 440 .

  5. #5
    Thats what i do also.

  6. #6
    Join Date
    Jan 2004
    Location
    Midlothian, Virginia
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    195

    how?

    if a capacitor can be thought of as a balloon and voltage a pressure. (electrical pressure that is) how can what you guys see occuring happen. the balloon ( capaacitor in this case) can't have higher pressure than the thing pumping it up. (the line voltage in this case)
    Goodbyee stranger it's been nice. Hope you find your paradise! Hey it aint rocket science, "It's a Trade !"

  7. #7
    Join Date
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    The voltage across the cap is from the start winding, not the line voltage.

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    How many times must one fix something before it is fixed?

  8. #8
    Join Date
    Jun 2003
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    The caps blowing up is a GE problem, they do this on every manufacturers unit in which they are installed, not just Goodman, the compressor manufacturer specs the run caps anyway

  9. #9
    'The caps blowing up is a GE problem, they do this on every manufacturers unit in which they are installed, not just Goodman, the compressor manufacturer specs the run caps anywa
    '

    ME: Not just GE caps either ; have found other brand caps where the voltage on them are considerably above the rating. Youd think these residental Compressor Mfg'rs would just go with all 440 v. rated caps, and be done with it.

  10. #10
    Join Date
    Feb 2005
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    GEORGIA
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    Oh, beenthere...
    You could take most of "us" back to school..
    This is very much understood...
    Thanks
    Peace,
    Stephen
    "Value our Differences"

  11. #11
    Join Date
    Jan 2004
    Location
    Midlothian, Virginia
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    195

    ok the voltage across the start winding is the voltage across the start capacitor.
    and guess what the voltage across the start winding is the line voltage.
    Goodbyee stranger it's been nice. Hope you find your paradise! Hey it aint rocket science, "It's a Trade !"

  12. #12
    Join Date
    Jan 2004
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    Not quite, but close.

    All motors are generators, and all generators are motors.

    The voltage from the start winding is an EMB, with is higher then the line voltage.
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    How many times must one fix something before it is fixed?

  13. #13
    Correct. A motor is like a generator in that it generates higher voltage known as BEMF or Back Electromotive Force ; This increased generated voltage comes thru the start winding and thru the wire leading to the Run Capacitor terminal . The other terminal on the RUn Capacitor is for the Run winding on the compressor (or fan motor...as the case may be). The rating of a Run Capacitor , such as 370 volts...must not be exceeded during operation. Its common to find Goodman A/C units all the time where the imposed BEMF voltage is higher than 370 volts. I think the highest ive ever found was over 400 volts .


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