I changed my heater frame, door, door motor and heater core. some time back and picked up some info that may help out. When at the Ford parts counter an experienced mechanic with the heater problems happened by. Seeing my heater parts on the bench he suggested to replace the DOOR DRIVE MOTOR with the new door weather you think you need it or not. He explained that the motor has limit switches built in and if one is bad, the motor will overdrive the door and brake it again. It is located on the outside of the plenum between the floorboard and the bottom of the plenum. TIGHT FIT on my expedition. Happy New Year ! Rich

 

How big of a job was it to replace? i switched over to defrsot the other day and somthing snaped. now it won't blow air out of the defrost vents.
Thanks for any help you could give me

 

If you are lucky the heater controll switch ( the one that you turn blue to red) is bad. Check it first with oammeter. If it is good - and your truck has a lot of miles on it it probebly needs a new heater blend door and while your in there change the heater core and the the motor that turns the blend door. Plan on your truck being out of use for 1 to 2 days. the dash must be pulled out on 6the right nside and a little out on the right side. Search down this forum and you will find an answer to this problem with a website to get full instructions as to how to do it. Good Luck. Make sure you bag and tag all screws and where they go. It will help a lot when you go to put the dash back in.