Blower won't stay on

Old 12-02-05, 09:23 AM
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Blower won't stay on

I have a forced air gas furnace. Was making vibrating noises through the ductwork last night and now the blower will come on for about a minute or 2 then shut off. This happens no matter what temperature I have the thermostat set at. Any help will be greatly appreciated. I am a single mom with 2 kids and it is pretty cold in Illinois right now!
Old 12-02-05, 03:32 PM
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Have you checked the air filter?

The blower motor may have gone out on you, and it's over heating and shutting off on your.
Old 12-02-05, 03:49 PM
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Turn off the furnace, first!

Then access the blower compartment and try to turn the blower by hand. It should spin freely like spinning merry go round. It ought to stay spinning, all by itself, if it's direct drive (directly connected to the motor as opposed to belt driven.) Can you tell if there are oil ports on it? You should at least be able to easily see the one on the far end of the motor that is not blocked out visually by the blower wheel. It will be directly above the end bearing and usually it has a cap that is only like 1/8 inch in diameter, may be silver or plastic yellow. Oil is Sae 10 or 20 weight (sewing machine oil/ 3m oil). If you see an oil port, let us know.

But many newer furnaces have sealed bearings and no oiling is required. You will not see any place to oil, and also most furnaces will say that no further lubrication is required, possibly right on the blower itself.

You should then try to run the furnace again and after it quits again, shut off the furnace!, then try to spin the blower wheel again. It may be harder to spin this time.

Are you familiar with mechanical things?/bearings? You can tell if the motor bearings are shot by grabbing the blower wheel and try to raise it up and down. But you have to know what you are doing as you can be decieved if you feel the end-play and think THAT is the unwanted bearing slop. End play is okay, and necessary. Up and down play is not. So in testing, pull on the blower wheel to dead-end the end play first; then try to rock the blower wheel up and down. If you feel the slightest play, especially with discernible clicking feeling as you do so, the motor bearings are shot. On direct drive blower wheels there are not any bearings for the blower wheel itself. Only do belt driven blower wheels have bearings.

IF it is the bearings and oiling doesn't do any good, as it's probably too late, you will need a replacement motor of a probable size of 1/4 - 1/2 horsepower and they cost like $75 -100, and are easy to put in (you have to take the old one with so you get the correct rating plus correct shaft diameter/length), if you can figure out how to get the blower out (usually there are only a few screws to remove) of the furnace and can manage to get the blower wheel off the shaft (that can be a real test, sometimes). If you need help with this, if it comes to that, let us know.

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