Furnace Blower

QUESTION:

I am having difficulties with my furnace and I thought I'd run the symptoms by you guys and see if anything pops in your mind.
It's a gas furnace.
When we first moved in 3 years ago, when you first turned the heat on, there would be a strong smell for about 3 to 5 minutes.. and it would go away. The land lord said it was normal. It didnt' smell like gas, more like, i'm guessng heating oil or something. I don't really know what it smelled like. I just know what gas leaks smell like and that wasn't it.
So that was just a normal part of heating for 3 years.
This year.. the heat smell coming into the rooms smells like something was burning.. like a strong smoky odor filled the house and the smoke detector went off. I immediately turned the furnace off because it was evident that was the source. I inspected the whole house.
after the house cleared out, either the same day or the next day I turned on the heater again to run some tests.. it didnt' smoke as bad as before.. but i sensed a light smoke odor.. then it seemed to get a little heavier, so out of concern I turned it off.
When I turned it off, actuall visible smoke came out of the vents. Also the heat would not come back on. So I went down stairs to inspect the furnace. One thing I noticed is that the circuit breaker and flipped, thus preventing the furnace blower motor? from coming on.
While I was down there, I was afraid maybe one of the wires was shorted out, so I moved them around a little. I didn't notice any shorts.
One other symptom i noticed was that the heater blower would only come on for 20 second increments. It would come on, blow for 20 seconds and cut out.. maybe 20 or 30 seconds (or a min?) then come back on and blow another 20 seconds. I noticed that when i was in the basement doing laundry.
also note that the household temperature no longer can reach over 72 indicated degrees at the thermostat control, even if we have it set to 90 or how ever high it will go. . We replaced the furnace filter
(properly) at the first sign of unusual odor i'd say a week or 2 ago.
Basicly the problem seems like the heater blower motor isnt' coming on for very long if at all. Before we could feel like a heated wind coming from the vents now all I feel is more like a trickle heat coming from the vents. A couple of the rooms are so cold I had to buy a small portable electric heater.
I'm wondering does this sound like the blower unit (technical name is?) is going bad? Or maybe some thermostat or controller for it is in there going bad?
Any advice diagnostic type of advice would be appreciated. I would atleast hope to learn what the possible (and probably) causes coudl be before I have a repair man come to diagnose it.. and if it's not too complicated maybe I will consider doing it myself, after all I do work on cars and my motorcycles, and know the general safety precautions to take working with the furnace and gas appliances, as I have lit them many times. I'm just hoping now someoen's experience can atleast give me an indication of what's wrong?

ANSWER:

You're right; the blower motor is at fault. The smoke was probably from overheated windings. The bearings may have seized (or blower if belt drive) or the motor has an internal fault. The motor has an integral thermal protector which is what is shutting it down periodically.
Time to lean on the landlord for a new motor...


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