Furnace does not come on automatically

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Old 04-29-10, 06:01 AM
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Furnace does not come on automatically

Forced air furnace - Bryant

Furnace does not go on automatically.

There is an on off switch next to the furnace. When I turn it off and then on the pilot lights up and the furnace works for a few minutes. Then it shuts down and usually does not restart.

If I hit the on off switch immediately after shut down I here the motor for a second before it stops, the pilot comes on, but turns off.

I noticed that at the end of they heating cycle the flames shut off and come on again numerous times before shut down.

Things I checked:

The flue seems to be clear, no debris at the bottom, light shines through from the top, using a mirror it seems clear. I can feel air being sucked up.

I took the CO heat sensor to the local heating supply store, they checked it and said it was working.

The blower motor felt warm when I touched the housing, I would not call it hot but I only touched the back of the housing.
 
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Old 05-08-10, 10:37 AM
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Blower wheel was fouled. So I cleaned it.
 
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Old 05-08-10, 05:24 PM
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Did cleaning it, solve your problem. Or are you simply adiding more information to the OP, and still need help.
 
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Old 05-08-10, 08:00 PM
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Yes cleaning it solved the problem. I think it lost suction, so it was not getting enough air. A sensor detected the engine getting hot and then shut the whole furnace down. Cleaning is was a chore to say the least.

A note to DIYs with old furnaces. Check the motor for oil ports. If it has oil ports there will be one on each side. If it does add some oil when you clean it. I never knew it had oil ports.
 
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Old 05-09-10, 10:54 AM
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I searched the net for terms like:

Furnace, Blower wheel, squirrel cage, cleaning, replacement.

Oiling a blower motor, Oil port blower motor, oil port electric motor.

There are a number of web pages on the subject.

The symptoms my furnace had were similar to those discussed on various web pages about fouled blower wheels. The amount of fouling did not seem like much, but it changed the shape of the blades enough that they were not throwing the air like they were supposed to.

I would advise drying parts immediately and sun drying so minimize rusting.

If your motor has oil ports: The oil recommended was BLUE LABEL 3-in-one. It must be blue label, the one with a picture of an electric motor on it. Evidently the other oils have additives that will damage the motor. So why not buy the right stuff ($3). When the motor started up I would hear a screech, I no longer hear it.

It might be interesting to record the sound of your furnace before you service it to see what the differences are.

An expert explains it better than I can:
Home Columnists Charlie "Tec Daddy" Greer It's All About the Blower
It's All About the Blower

It's All About the Blower
 

Last edited by geo8rge; 05-09-10 at 12:52 PM.
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Old 05-10-10, 06:12 PM
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Thanks for your reply - and information to help others.
 
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