I have an 02 screw witht the 5.4 and I have searched this problem but none of what i came up with seem to match my problem... the heater wont blow out of the floor vents all other settings work just fine and blows hot air just nothing on your feet. I dont know if the previous owner had changed radios before I bought it and maybe knocked a vac line off or what but I dont think so. all other settings seem to work just fine any help out there?

 

sounds like the selector door isnt moving properly. check under the dash real carefully and look for anything out of place or missing.