The other day smoke started coming in the right side duct on my 1988 150 Econoline. Smelled like insulation burning, but not absolutely sure. I shut off engine immediately and waited five minutes, then drove home and parked. Next day I starated it. AC and blower still work fine. Whats the easiest way to find the origin of this smoke? Is it possible an obstruction could have caused the fire and if so, what could get hot enough to start the obstruction on fire?

 

Pull the fan motor--what else could it be? Wires to the motor or motor itself. Overheated motor will smoke and live to tell the tale if shut down quick. Not long to live after that, though. Motors are cheap. Mine went haywire on my '85--no smoke, but noisy. Good luck.

 

Sometimes debris will find it's way to the blower motor speed resistor assy. When it hits those hot resistor wires smoke is produced. Sometimes the airflow to the resistor is cut off and the resistor assy melts or melts part of the housing.

You will need to take your blower motor and heater box assy apart.

 

Thanks guys! Is the blower in the box below the dashboard or will I have to take it off also? I don't have a shop manual so don't know where to begin.

 

Torque1st was right on. A friend showed me how to take out the blower motor and get at the heater box. Sure enough leaves had built up high enough to touch the resistor unit. Blew it and associated ducts out and no more problems. Took about two hours. Thanks again!