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  1. #1
    Join Date
    Oct 2011
    Location
    Cicero, IN.
    Posts
    48

    Condenser Fan Running All The Time

    A little 3 ton unit. 460 volt. The condenser fan is running all the time and the contactor is not pulled in, I pick the fan shroud up and fan goes off. The compressor is 3 phase and has a double pole contactor. Reading 17 volts on the motor leads to fan motor that is running. 277 to ground on both fan motor leads. I believe fan motor is going to ground and running on the voltage coming through the 3 phase compressor as the fan motor is single phase. I am replacing the fan motor tommorow. Fan runs just fine also when the compressor contactor pulls in. I thought I should go to selling fries at McDonalds after this one.

  2. #2
    Join Date
    Apr 2012
    Location
    lexington, NC
    Posts
    32
    Ohm your motor wires to ground to see if it is indeed grounded.

  3. #3
    Join Date
    Dec 2002
    Location
    SouthEast NC ICW & Piedmont Foothills
    Posts
    7,635
    what's your voltage out of fan relay/contactor?

    you sure contactor is open on both legs?
    It`s better to be silent and thought the fool; than speak and remove all doubt.

  4. #4
    Join Date
    Oct 2011
    Location
    Cicero, IN.
    Posts
    48
    Not showing any ground. It did zap me while playing on/off while raising and lowering the lid. No wires touching.

  5. #5
    Join Date
    Oct 2011
    Location
    Cicero, IN.
    Posts
    48
    17 volts with contactor not pulled in. 483 pulled in.

  6. #6
    Join Date
    Apr 2004
    Location
    MN
    Posts
    1,838
    Something sounds fishy. The third leg doesn't run through the contactor? Can't say I've seen that before, although, I haven't seen everything there is to see. The fan doesn't show a path to ground? You got shocked lifting the lid off, indicating something is shorted to ground. Is the unit properly grounded? No bare wires shorting to case? Does the compressor show a path to ground on the unswitched lead?
    A Veteran is a person, who at some point in their life, wrote a blank check payable to the United States of America for payment up to and including their life.
    Gene Castagnetti-Director of the National Memorial Cemetery of the Pacific in Hawaii

  7. #7
    Join Date
    Oct 2011
    Location
    Cicero, IN.
    Posts
    48
    Yes the 3rd leg is hot all the time thus feeding voltage through the winding and to the one leg of the motor on the load side of the contactor. Trane

  8. #8
    Join Date
    Apr 2012
    Location
    lexington, NC
    Posts
    32
    whats the voltage on the motor? Is your motor grounded properly?

  9. #9
    Join Date
    Oct 2011
    Location
    Chicagoland Area
    Posts
    4,828
    You're backfeeding from somewhere. Had the same issue with a 230v Trane but for the life of me I don't remember what I did.
    Officially, Down for the count

    YOU HAVE TO GET OFF YOUR ASS TO GET ON YOUR FEET

    I know enough to know, I don't know enough
    Liberalism-Ideas so good they mandate them

  10. #10
    Join Date
    Feb 2006
    Location
    Atlanta,GA.
    Posts
    926
    what about the cap is it good?

  11. #11
    Join Date
    Oct 2011
    Location
    Cicero, IN.
    Posts
    48
    I am glad my coworker was with me to witness this. Funny how the fan motor speed decreases when the contacter pulls in and supplies the normal 460v to the motor. I did not pull the grounds loose at the disconnect to test if the ground was properly landed in the breaker panel.

  12. #12
    Join Date
    May 2004
    Location
    SE Pennsylvania
    Posts
    1,008
    More then likely one of the windings in the motor has high resistance path to ground, that's why the motor stops when you lift off the cover. What ohm range is the meter your using, 400 ohm typical Fluke clamp on? If so you will not see the short, 460 and 277 will jump much higher resistances.

  13. #13
    Join Date
    Oct 2011
    Location
    Cicero, IN.
    Posts
    48
    I had my $450 dollar Fluke laying there taking temperature readings and I was using the U shaped Volt/Amp/Ohm meter for my other reading's. My coworker is changing out the motor today. I will have him save me the motor to check the resistance on Monday and get back at you guy's. Thank's for the input. Haha my brain said WTF it's got to be the motor.

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