I have a 98 f150 4.6 ext cab. i have a noise coming from what sounds like inside the dash, i cant hear it in the engine bay. it is non stop, from when i crank it to shutting it off. it sounds like a fan is wobbling really bad, and it lasts maybe for like half a second after i shut the truck off. but i never use my heat cause its 900 degrees here everyday. ive read about people saying its the heater core, but ive been reading people's post with heater core problems always have a smell coming through the vents. there is not coolant smell in my truck, and my heat works great, but i do have a ac bypass pulley, so no ac. but this has been going on long before that.

any help would be greatly appreciated!

 

Turn the climate control to OFF, wait 10 or 15 seconds, then switch the engine off and listen. It might be the blower motor.

 

ive done that already. its always on off. i havent turned it on in a long time, no need to. too hot, and my ac doesnt work. and with climate control on low or high the noise is still there.