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  1. #1
    Join Date
    Aug 2003
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    574
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    Carrier 3ph motor humming

    I am the second company at this rooftop problem was called by a friend that works there and i said i would look at it. carrier #48HJE008 460/3ph the indoor contactor and fan motor were changed and when it starts all it does is hum with no rotation.i double checked the wiring and all checked out,when i start checking voltage i have 260volts at both side of the contactor and there was a yellow motor wire that had voltage to it that was connected to the line voltage side of the comp contactor.not sure where to go with this one also when i jumper r-w to get the heat cycled started it will fire but when i remove the jumper it will not shut down

  2. #2
    Join Date
    Aug 2012
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    3,247
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    It sounds like it's stuck or is single phasing but you only checked two wires on each side of contactor you need to check all three wires for a three phase compressor.
    It's not if your doing it right it's whether your doing the right thing that is important.

  3. #3
    Join Date
    Aug 2003
    Posts
    574
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    Its the indoor fan motor I am having the issue with.I have 260 volts at all three wires to ground

  4. #4
    Join Date
    May 2011
    Location
    Spring City, Pennsylvania, United States
    Posts
    209
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    Sounds like it's single phasing. Bit you need to verify your phase to phase voltage not to ground.

  5. #5
    Join Date
    Aug 2003
    Posts
    574
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    So check voltage where the two wires are on the contactor?

  6. #6
    Join Date
    Jan 2010
    Posts
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    How many wires go to the motor ?

  7. #7
    Join Date
    Sep 2011
    Location
    In the truck
    Posts
    530
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    Check and see if the motor they replaced is dual voltage. May have it wired for High voltage instead of low voltage etc. 260 volts are you sure? Im familiar with 208/230, 277, and 460. What voltage do you show when checking L1 to L2, L1 to L3, and L2 to L3?

    Does it have a overload? Check and make sure power is passing through the overload with your meter. Also does it have a frequency drive?

  8. #8
    Join Date
    Jan 2010
    Posts
    10,512
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    Sounds like 2 legs thru contactor and 1 leg dedecated hot.

  9. #9
    Join Date
    Jun 2014
    Location
    Dover, DE
    Posts
    6,129
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    It's a 3 phase motor, so make sure there's 3 phases of power being supplied.
    Carrier loves to use widow maker 2 pole contractors for 3 phase motors. That third leg is constantly powered. And it bites even when the motor isn't running.
    Your confusing yourself measuring to ground. Phase to phase only.
    I havent failed. Ive just found 10,000 ways that wont work. - Thomas Edison

    Its not whether you get knocked down, its whether you get up. - Vince Lombardi

  10. #10
    Join Date
    Sep 2013
    Location
    Wi
    Posts
    240
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    Should'nt you have 460 volts for 460 motor check a to b a to c and b to c if 460 check the bearings or replace motor.

  11. #11
    Join Date
    Jan 2010
    Posts
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    Quote Originally Posted by splus View Post
    indoor contactor and fan motor were changed
    ^^^^^^^

  12. #12
    Join Date
    Aug 2003
    Posts
    574
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    Yes its a two leg contactor and the other leg is hot all the time,what voltage should i be reading between both contactor legs and then each of these to the other hot leg?

  13. #13
    Join Date
    Aug 2003
    Posts
    574
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    it was a direct replacement motor and shows 40 on the tag

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