| This furnace has a circuit board in front of the fan motor. When you turn the power on, you should hear a "clunk" of a relay closing, and when you turn the 120 volt power to the furnace off, you should hear that relay open. Try turning the power on and off several times to see if you hear that relay opening and closing.
If you don't the relay on the cicuit board may have failed which would require a replacement. Good form would also suggest having a knowledgable repairman inspect for other possible cause of this kind of problem before replacing the circuit board.
If you can take a good close up picture of the circuit diagram on the cover of the fan compartment and display it some place, that would be helpful as well. |