Lennox gas furnace problem


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Old 11-14-09, 08:23 AM
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Lennox gas furnace problem

Hi, I have an old Lennox gas furnace:

G12D-110-2
524,827W

Litho, USA

I recently turned on the heat in my home, but after about 10 minutes (maybe?) a bad smell started coming though the vents. At first I thought it was just a result of the first run of the season. After a few minutes the smell was so bad I had to turn off the heat and leave the house.

The smell was like the smell when something electronic blows (I blew a computer speaker once with the wrong power adapter).

The next time I tried turning on the heat the furnace failed to turn on. I checked it out and the fuse had blown. I replaced it and the furnace will turn on now, but the blower never activates. The gas turns on for a few minutes and turns off and the AC unit will turn on, but no air flow.

I want to diagnose and fix this as much myself as possible. How do I go about figuring out what's wrong? I don't think the blower is broken because it was still working when the bad smell was circulating. But that's just speculation.
 
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Old 11-14-09, 11:10 AM
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Do you have a meter?
Isolate the wires to your motor and measure each lead for continuity to ground. Then measure the resistance between your leads.

YouTube - how to bench check a central A/C blower motor
 
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Old 11-14-09, 11:40 AM
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Changing out a blower motor, if it comes to that is job very DIY-able, if you are at all mechanically inclined. (To give you an idea: By removing as little as 6 bolts-screws only!, you can have the blower assembly out and motor separated from the blower assembly. 2 to hold in assembly, 3 that hold motor to housing, 1 that holds blower to motor shaft.) Some may require 2 more screws removed to move control panel box out of the way first. I'm to the point I can do these jobs blindflolded in the dark with one hand behind my back

You can get comparable motors of the same horsepower and speed(s), at a motor shop, for usually more reasonable than getting some exact OEM at an HVAC business.
 
 

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