Do not try this dyi this is absolutely a professional job. There are many safety considerations for working on gas furnaces!
Case: Homeowner smelled burning and then no heat. They used a space heater to get by. It was very cold.
I went under the house to check and this is what I found: The furnace board was blinking to indicate a limit switch activation. I opened door and but manually pushed the door switch to restart the unit blower motor only hummed I checked the Capacitor with my multi-meter to see if it was good It was rated 7.5 mfd and read a little more than that. It was OK.
Next I checked the blower motor itself. Wow! it was burning hot and loose inside its bracket. That was the problem I had to remove the furnace board, then slide the blower out The unfasten all of the wires Then drag it 25 ft to the outside of the house. (on my hands and knees-that's why they call it a crawl space!) I carried it out to my truck and located the blower motor I had in stock. That saved me a trip!.I removed the bracket screws that held the motor inside the squirrel cage and then removed the nut that attached the motor to the fan wheel. I then reassembled the blower and this time I put it in the correct bracket and the motor did not move around like it had been. Now back under the house and crawl 25 ft to the furnace. I slid the blower back in place and rewired it correctly this time (the wires were wrong before) by stripping the ends and using new end nuts. I tested it and put the cover back on and taped some of the duct work back in place.
The furnace is working great and everyone is happy and I made a new friend!!! This one was $350
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