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    richardlbj's Avatar
    richardlbj Posts: 3, Reputation: 1
    New Member
    		  
    #1

    Jun 20, 2010, 08:04 PM
    Ac fan does not start as compressor runs
    At first both fan and compressor didn't start and the unit was humming. I turned off circuit breaker, replaced capacitor (5/40 370V), turned on circuit breaker.

    The current situation is:

    When I turn on the unit by switching from off to cool at thermostat, compressor runs but fan wouldn't start. Fan moves slightly then stuck. I try pushing blades and it doesn't help. I feel resistance when pushing the blades. Compressor shuts off by itself in a few minutes.

    The blades move freely when the unit is off.

    While I reconnecting the capacity, I did Fan, then HERM, then accidentally touched C wire to HERM, then connected C. Could the "touch" caused any damages?

    What should I do from here?


    Thanks,
    Richard
    hvac1000's Avatar
    hvac1000 Posts: 14,540, Reputation: 435
    Heating & Air Conditioning Expert
    		  
    #2

    Jun 21, 2010, 09:45 AM
    I believe the fan motor is probably toast but proper electrical testing is in order.
    richardlbj's Avatar
    richardlbj Posts: 3, Reputation: 1
    New Member
    		  
    #3

    Jun 21, 2010, 02:51 PM

    What tests can I do and what tools would I need to find out if the fan motor is bad...
    hvac1000's Avatar
    hvac1000 Posts: 14,540, Reputation: 435
    Heating & Air Conditioning Expert
    		  
    #4

    Jun 21, 2010, 09:12 PM
    Quote Originally Posted by richardlbj View Post
    At first both fan and compressor didn't start and the unit was humming. I turned off circuit breaker, replaced capacitor (5/40 370V), turned on circuit breaker.

    The current situation is:

    When I turn on the unit by switching from off to cool at thermostat, compressor runs but fan wouldn't start. Fan moves slightly then stuck. I try pushing blades and it doesn't help. I feel resistance when pushing the blades. Compressor shuts off by itself in a few minutes.

    The blades move freely when the unit is off.

    While I reconnecting the capacity, I did Fan, then HERM, then accidentally touched C wire to HERM, then connected C. Could the "touch" caused any damages?

    What should I do from here?


    Thanks,
    Richard


    An Amprobe will tell you right away because a defective motor will have a very high current draw,higher than the listed draw on the info tag for the unit.

    Do not keep testing with the compressor active or it might damage the internal overload since you mentioned it shut off by itself.
    JimmyTheAirGuy's Avatar
    JimmyTheAirGuy Posts: 15, Reputation: 0
    New Member
    		  
    #5

    Jun 21, 2010, 09:19 PM

    Get an ohms meter and check continuity between leads on your fan motor. Then go over the wires and make sure it is wired correctly especially the run capacitor. Usually when the wires are arched by error it will trip the breaker but not damage the motor. It sounds like if any component is damaged it is going to be your run capacitor.
    Good Luck and God Bless
    Jimmy The Air Guy
    lloyd212's Avatar
    lloyd212 Posts: 2, Reputation: 1
    New Member
    		  
    #6

    Apr 30, 2012, 11:12 AM
    Compressor runs, but fan doesn't. Two different capacitors, (45, 7.5) both read 0.1 MFD. I check with Ohmeter, 7.5 capacitor is reading 37... 45 capacitor reads 2.4... Fan blade turns freely. What could the problem be?
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