Furnace comes on (flame) but not blower, then trips out on overtemp. This is an intermittent problem that occurs infrequently, every couple of days or even a month. Last week fan would not run at all, repairman replaced the module on the motor and all was fine for 3 days and now back to the intermittent blower not running. I just power down the furnace and then power back up and all is fine till the next time. Any guesses what might be the problem??
Problem Motor, motor lead connections or board.
Trying to see if the motor is being powered or not, when it should be running but isn't, when the problem is intermitant is difficult.
Right now it sounds like your blower intermitantly fails to run, furnace overheats and locks out. You turn off the power thereby resetting the now cooled furnace and everything starts up fine again. Amp testing the motor may give you some clues with a long heating run.