I have a question and I know I came to the right site to get an answer!!! I have an 03' F-150 supercrew with a 5.4L and now that it is winter here in minnesota I have noticed or should i say my wife noticed I don't have any heat coming out of the floor vents no matter how many times I try the push button...I also tried the flr/dfrst, pnl/flr bottons and they don't work...other than that it seems fine the thing blows heat like crazy but nothing on the floor...any help would be greatful...like I said after reading a bunch of posts I came to the right site to get some help...thanks

 

Hey, I have an 03 Screw. I have the same issue. I can only get heat out of the upper vents, nothing on the floor specific. I read the owners manual and found nothing on it. Evidently its "a Ford thing".

 

Hmm, my '03 screw blows out the floor just fine. Mine's an XLT with the "manual" *****. But it keeps my toes nice and toasty.

 

i dont know the details, but there are a couple doors in the air path by the heater. the doors i believe are vacuum operated to open and close. they direct the air "up" or "down". when you turn the **** from floor to panel to defrost, you can hear the doors stroke. try to move and see what you hear. i am guessing the door is stuck, or the vacuum hose is off and the door is always pointing to the defrost.

 

i have a factory service manual on CD rom- just checked it for the basics. as i said, itis all vacuum controlled. intake manifold makes vacuum and there is a vacuum chamber, maybe behind the battery (according to the CD) and a vacuum hose runs thru the firewall to the instrument panel. the ***** align ports and make the vacuum go to the heater door, inside-outside air door, and air conditioner door. it appears the floor heat door needs vacuum to engage it. if the door sticks or you have no vacuum, then the air is directed to the defrost as a safety thing so windows dont fog up. i dont know what the common mode of failure is on this truck, but you need vacuum to the lower door cyliinder and the door must not be stuck. book says you can see the vacuum cylinder connected to the lower door if you remove the floor panel over the heater, under the dash. like i said, you should be able to move the levers and hear the vacuum pulling the different cylinders open and closed. if you hear nothing, i would look for a vacuum hose problem. it you hear some doors moving, but dont get air to the floor, then look behind the plastic panel under dash at floor level.

 

Check around the front passenger foot area and in behind the glove box for a vacuum hose that has come off.