Saturday morning I awoke to the smell of overheated wiring. After searching the house for the source of the smell, I determined the problem lay with the heater. Later, I opened the unit and found a piece of insulation had fallen on top of the blower fan housing, which I surmised had restricted air flow and had caused the motor to overheat. I used Liquid Nails to re-affix the insulation, and tested the unit again, and found the odor persisted. My hypothesis was the motor had heated beyond the breaking point and would need to be replaced. Today, I took the fan housing and motor to an electric motor repair shop, where they replaced the Emerson 1/3 hp motor with an Emerson 1/2 hp motor. They provided a new two pole capacitor, to replace the 3 pole that was part of the assembly. I eventually rewired the assembly using the original capacitor. After re-installing the housing, fan, and new motor, I successfully started the furnace. After running it for a few minutes, I began to smell hot wiring again. I ran the unit long enough to heat the house from 60 to 72 degrees, then turned the unit off, as the smell had grown strong enough to give me a slight headache. The smell was in some ways a little different, not as acrid as the original odor. I thought it might be a "breaking in" smell. I haven't run the unit since about 4 this afternoon.

Perhaps there may be someone who could give me some advice about what might be causing the new motor to overheat. Any comment or additional questions are welcomed.