2003 F-150. Heater will only blow to the windshield. The dash says panel, floor ect but only blows one way. Any suggestions on how to fix and part #.
Thanks

you have a vacum leak eather a hose leaking or a falty vacum switch. look for a broken hose or one that has fallen off. if you don't see one then remove a vacum hoses and plug it off if the selector switch change were the air comes out then you've found the falty vacum swith. if not try a diferent hose