Hey there. The fan in my '90 F-150 is blowing incredibly weak, except in one spot on the defroster, and it's not very hot at running temp. I'm assuming it's a plugged heater core. I pulled off my glove compartment today and it looks like I'm gonna need to rip apart my whole dash. Has anyone done this type of job before, and is there a good way to do it without ripping apart the dash?

 

You don't rip the dash apart to replace the heater core on a 1990 Ford truck, not even close. It was designed to make replacing the heater core about as easy as possible, unlike the 1997 and newer Ford trucks where you have to remove the dash. A Haynes repair manual that includes your year truck gives good step by step instructions. You may be able to find some good writeups on the internet.

 

Alright, I'll have a look for a guide.

Thank you

 

Is the blower motor spinning slowly? Or is it spinning full-speed, but not moving any air? Is there air coming out the defrost register?Do you mean one of the registers at the front of the dash? Or one location on the control near the DEF position?Never assume - diagnose. But it's much more likely that the evaporator is blocked because that's the first thing the air has to go through after the blower. Pull the blower motor out (4 8mm screws) and look at the evaporator fins.No, just take out those 8 8mm screws.Follow the links in this caption:

(click this text)