Here we go again... This old 91 F150 is driving me nuts. This isn't a real deal breaker, but it still bugs me. The fan for the A/C and heater is either off (in the 3 lowest settings) or on (full blast). Is this the dash control, or would it be the blower, or something in between? Thanks for any guidance!

 

Suggest that your blower motor resistor has failed. Hi-speed bypasses this resistor block, thus the reason the fan still works on that setting. Should be a separate module up under the dash somewheres - follow the wiring from the control panel switch to the blower motor.

 

Thanks! Next time I have a chance, I'll see what I can find.

 

wde3477, you were right on! The resistor was mounted right on the blower housing, which was even better. $18 part, 2 screws, 5 minutes, and it works... Why can't they all be like that??? Thanks!