overheating blower motor


  #1  
Old 07-31-10, 12:09 PM
J
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overheating blower motor

I am replacing my blower motor on my central air. I got it switched it with the old motor and put the new capacitor in just fine and it worked for a half an hour or so and then it turned off. I yanked it back out and the motor was very hot to touch and I smelled a little smoke in the air. I thought I got a bad motor so I got a new one and the exact same thing happened; it will work for a few minutes get incredibly hot to the touch, then turn itself off. Since it was the same capacitor I yanked it and I tested it, the capacitor is fine.

I went and made sure all the wires were insulated properly and there were no shorts and everything was screwed into the board correctly.

But the problem persists. Every time I install it, it super heats and shuts itself off. I am hoping someone can tell me what I am missing.
 
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Old 07-31-10, 12:59 PM
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Is this the indoor or outdoor fan?

Does the new motor have the same or larger hp rating as the original? Same rpm?

There still could be problems with the cap - testing at low voltage doesn't prove it's OK when run at normal voltage. I would always replace the cap when replacing the motor.
 
  #3  
Old 07-31-10, 01:07 PM
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The new capacitor came with the first new motor. It is the indoor blower motor the one that is in the "squirrel cage”.

They old motor and the new one are both quarter horse. The old one is 1050 / 3 speed and the new ones are 1075 / 3 speed so that doesn’t seem like a huge difference to me.

I noticed that the rotation of the fan was going the wrong way so I flipped my rotation selector wire harness around so now the fan rotates in the right direction. It doesn’t seem that that would be the cause of over heating it just seems like that would affect the amount of air going through the ducts. I am not sure.
 
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Old 07-31-10, 01:53 PM
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Does the motor/fan turn freely by hand?
 
 

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