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    Twisted Jerk's Avatar
    Twisted Jerk Posts: 1, Reputation: 1
    New Member

    Jul 4, 2006, 08:44 AM
    The blower motor on my furnace cuts out when I turn on the AC. I have the unit set to run the fan continuously and when turning on the AC the fan quits.
    The motor is a direct drive to the squirrel cage. I cleaned the cage and motor and reinstalled. The motor runs but does not seem to be moving much air. It still cuts out when turning on the AC. It sounds as though when turning on the AC there is a power draw from the motor as it tries to keep running but is overloaded and stops. When turning the furnace on the blower continues to run but still at the reduced rate. The wiring all looks intact and undisturbed but I do smell that "electrical burn" odor after turning on the AC. No odor when running the furnace. I'm hoping it's just a worn out motor and I can replace it. The furnace is an older Lennox about 1982 and I can't afford to replace it now. One last thing after the motor cuts out from turning the AC on it will start 15-30 seconds after switching off the AC.
    Thanks for your help.

    Could this be a problem with the capacitor?

    Checked voltage in wires from motor and all have power before and during initiation of AC. When AC cycles on sparks fly from rear of the motor and it shuts off when it overheats.Re-starts after shutting off AC. I think this is definitely the motor as all wires and grounds are intact. Any thoughts? Please? Was able to see the sparking now that I have someone to help with thermostat upstairs.
    letmetellu's Avatar
    letmetellu Posts: 3,151, Reputation: 317
    Ultra Member

    Jul 8, 2006, 09:32 PM
    Sorry that I have not answered sooner but I was gone over the 4th.
    I did not understand completely what happens and when.
    First are you talking about the motor in the furnace, I assume you are.
    Second if you have everything off and you turn your fan to the on position what happens?
    Third what happens if you have the fan switch in auto position and then turn to ac and the thermostat is set for the AC to Come on.
    Forth if you did numberr three above and the motor came on how long did it run. And if it did cut off did it ever come back on by itself.
    Fifth if the blower does not run do you strt to get frost on the big line going from the AC.
    fenbach's Avatar
    fenbach Posts: 1, Reputation: 1
    New Member

    May 31, 2007, 07:10 PM
    Try oiling the fan motor.

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