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  1. #1

    Question Furnace blower will run but won't start by itself... capacitor?

    Hello all,
    I have a comfort-aire patriot 80 plus oil fired furnace. The problem I'm having is the blower fan won't start by itself, if I take the inspection cover off and start the squirrel cage myself it runs and will run fine through the cycle, until the next call for heat and the problem persists. Is there a way to tell if its the capacitor or the motor?
    We just bought the house in June and this is the first time we have needed the furnace. I think the system was sparingly used over the last few years as the previous owner burned wood also. The basement gets quite humid through the summer, when I first fired the unit and purged the air from the lines you could here a slight hum coming from the motor like it was trying to start. I shut off the power and tried spinning the squirrel cage and it wouldn't spin until I applied some force, then it broke free and spun freely. I'm hoping it isn't the motor..... any advice is appreciated.

  2. #2
    Join Date
    Jun 2001
    Location
    Moore, Oklahoma, United States
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    4,222
    Could be the motor, capacitor, or even wiring. A tech can can test it and find out which it is.

  3. #3
    Join Date
    Feb 2010
    Location
    Calgary, Alberta
    Posts
    1,104
    Replace the motor. If it was seized and and now can't start itself, it's cooked.
    Your meter should be able to test the capacitor.

  4. #4
    Join Date
    Feb 2010
    Location
    Calgary, Alberta
    Posts
    1,104
    Quote Originally Posted by syndicated View Post
    Replace the motor. If it was seized and and now can't start itself, it's cooked.
    Your meter should be able to test the capacitor.
    Oops, you probably don't have a meter. Lol.

    Get a tech to replace the motor.

  5. #5
    Join Date
    Jun 2001
    Location
    Moore, Oklahoma, United States
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    Quote Originally Posted by syndicated View Post
    Oops, you probably don't have a meter. Lol.

    Get a tech to replace the motor.
    A bad capacitor or no power to the start winding can cause the same result, may not be the motor.
    Have a tech check it out before just replacing the motor.
    Of course if the motor feels stiff and is hard to turn, time for a new motor.

  6. #6
    Actually the motor spins rather freely now. As far as a meter yes I have that, I worked as a contractor for years until becoming disabled, even worked as an electricians apprentice so I know my way around meters. Being on disability money is tight so I'm just looking for a little advice.
    Now if I'm going to test the capacitor what am I looking for? Voltage going to and from it? resistance?

  7. #7
    Join Date
    Dec 2008
    Location
    Buffalo NY
    Posts
    3,083
    Quote Originally Posted by Doug_G View Post
    Actually the motor spins rather freely now. As far as a meter yes I have that, I worked as a contractor for years until becoming disabled, even worked as an electricians apprentice so I know my way around meters. Being on disability money is tight so I'm just looking for a little advice.
    Now if I'm going to test the capacitor what am I looking for? Voltage going to and from it? resistance?
    Check MFDs with your meter. Caps are cheap to change.


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  8. #8
    Join Date
    Nov 2006
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    Southeastern Pa
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    I think the bottom line is that if the value on your meter agrees with the cap label value within 10%, then you should replace the motor. It IS possible that you have an open aux winding.
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  9. #9
    Join Date
    Jun 2001
    Location
    Moore, Oklahoma, United States
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    4,222
    I'd replace the cap first, if it ends up being a motor you will want to replace the cap anyways. Caps are cheaper than motors.

  10. #10
    Join Date
    Feb 2012
    Location
    Toronto Canada
    Posts
    1,090
    X2 I lost count on how many times I have made a new customer cause the Tech before me tells them crazy amount for motor cap etc and i come along and replace cap and it works fine. Test cap first.

  11. #11
    Join Date
    Jan 2004
    Location
    Lancaster PA
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    67,925
    Seems like a lot of DIY info.
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