Fan slow starting


Old 01-12-01, 08:11 PM
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I have a Trane underhouse gas furnance. I hear the pilot lighting the gas, and the element warming up before the fan starts to circulate.

The problem is, there is an occasional buzzing sound as if the fan motor is trying to start up. After 15 or so seconds the motor will start running and seems to run fine. This does not happen during each cycle but about two or three times in the evening. Also twice this past week when I have come home, the main circuit breaker has kicked off.

Could the problem be a bad capacitator, or could the motor be going. The furnance is about 7 years old.

Thanks in advance for your help.

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Old 01-12-01, 08:43 PM
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Buzzing sound or more like a loud hum? Watch the machine when it makes this sound. Verifiy it is the motor. I would change both and be done with it. If the run cap did go bad, you've been stressing the run windings.
Old 01-12-01, 10:53 PM
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Lightbulb Oil It

Hi: Richard

Not knowing the year of the furnace, it may be an older model with a fan motor that is suppose to be oiled. Check the fan motor and look for oiling caps or holes on the motor.

If the motor is the type that has an oil cap or hole above the bearings <on the outer edges> unplug the furnace first, drop in a few drops of 3 in 1 oil. Then hand spin the fan cage. Check if more oil is needed and repeat.

Then clean the entire fan cage area. Check the fan cage bearings for need of oil also. Oil them while your there.

Plug the unit back into the electric power. Turn the thermostat up and retest. If all goes well, the motor may only have needed a lube job and not need to be replaced.

If this works, oil those two locations twice a year and keep the air filter clean. If you have to replace the motor, replace it with a permanently lubed motor.
Old 01-13-01, 09:38 AM
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Sounds like the bearing could be staring to go bad. Since it is still running I would recommend oiling the motor with a #20 non detergent oil. Be careful if you by a 3-1 oil that you get motor oil. The capacitor could be starting to go bad, it doesn't cost much, just make sure you get the one the motor calls for, I've seen were the manufactor put the wrong one in there.
Mr Foster
HVAC Contractor
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