Furnace dead (blower?) GAS furnace

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  #1  
Old 01-06-09, 08:15 AM
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Furnace dead (blower?) GAS furnace

last night it seemed as though I smelled something burning.

I woke up this morning, the house was very cold even though tstat was set(furnace ON). Verified that the pilot was working as well as burners, but blower was not turning on.

Can I assume that my blower motor is shot and needs to be replaced, could it be part of the electric relay/switch?? Any thoughts, can I repair it myself, I consider myself pretty handy.


thanks very much
 
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Old 01-06-09, 09:25 AM
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forgot to mention a humming sound when I first went down to check. I also verified the breaker was OK.
 
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Old 01-06-09, 09:29 AM
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I'd start by listening carefully at the furnace for a noise suggesting that the fan motor is trying to start and failing.

There is a temperature limit switch in the fan motor that shuts it off if it overheats. It usually takes five minutes or so to cool off, and then you may hear the electricity try to start the motor again --- and fail.

If that's what you hear, you can open the flower compartment and try pushing the fan wheel. If it's stiff and doesn't move freely, the motor failure may be because of lack of lubrication.

You may find one oil port visible on the blower motor, which would prove that the motor is designed to be oiled (some are not). If that's the case, I'd try oiling the motor.

But oiling one side isn't adequate. Usually to oil the other side requires removing the fan assembly from the furnace and then removing the motor from the fan assembly, which will probably take an hour or so to do.

Even then, the motor may be damaged enough not to work and may require replacement. If it were me, I'd give it a try, though.
 
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Old 01-06-09, 09:43 AM
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it funny that you mention oiling because there was an oil can(3in1) near by when we moved in. I tried adding oil last year, but probably didnt add nearly enough as I wasnt certian where to add it.

What should the oiling port look like and where is it located?
If it requires taking apart I will do that.
 
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Old 01-06-09, 11:36 AM
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Usually there are two oil ports for the bearings on each side of the motor. If you look at the end of the motor exposed from the fan cage, it should be near the end of the motor.

Often it will have a small cap held closed by a spring. Other times there may be a piece of narrow plastic tubing that leads oil to the bearings. You may see two tubes, one of which lubricates the easy to get to bearing and the other that conducts oill to the hard to get to bearing, saving you disassembly of the fan.

If there is no oil port, the motor is probably permanently lubricated. The fan motor in my furnace is permanently lubricated and has been running as needed since 1962.

Other furnaces I own or maintain I lubricate every 5 years if I have to disassemble the fan. If you have air conditioning or run the fan continuously, it may need oiling more often.
 
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Old 01-06-09, 11:41 AM
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There is generally a wick in the motor which absorbs oil and then it gradually gets used up lubricating the motor.

So i generally spend a couple of minutes adding whatever oil the oil ports will accept.

Some motors or owner's manual's will provide more detail on recommend amounts of oil and frequency of oiling. But the methods I describe have worked for me --- I've never replaced a blower motor in equipment I was responsible for maintaining.
 
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Old 01-06-09, 11:42 AM
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No Pro, but I've seen plugs in the oil ports as well, either metal or plastic that have to be pried or twisted out.

Also, is it possible that the capacitor (small round or oval can with wires attached to motor) for the motor has failed (if it has one)? If the fan spins freely but only hums when powered up, that would prob be what I'd look for. If you can safely do it, try powering the fan and giving it a spin with a stick or similar. If it starts and runs, look for a cap.
 
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Old 01-06-09, 06:04 PM
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I actually got a little messy and removed the motor and really lubed it up well, although it mangaed to start even before I did this I went ahead anyway, and now its been working for a couple of hours.

I am a little nervous that this was the only problem but hopefully it will hold up through the winter.

I guess since it has no problem starting up the capacitor and switches are all OK right??.


thanks for all the very helpful commentts and ideas
 
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