2001 F150 5.4 4wd - AC not working but when I turn the temperature dial to the blue side and turn on the fan, super hot air comes out of the vents or wherever I direct the fan to blow (Floor, defrost, etc) I know it shouldn't blow ice cold especially since my AC doesn't work but.....shouldn't I feel a temp change coming from the vents when I move temp dial from the red area to the blue? It's max heat wherever I have it set. Any ideas??

 

Since your AC does not get cold, you will not likely notice much difference in the full cold or full hot settings in the middle-of-summer heat.

Your truck uses an air box that blends the heated or cooled air.
The "blend door" is the partition the selects whether you get hot or cold or the "blend" of each somewhere between hot and cold.

The door can break, most commonly at the hinge. The factory original type one piece blend door is under $20 retail.
There is also a 2 piece door that is allegedly easier to install by cutting a hole in the air box behind the glove box. Ford F150 '97-'04 - '97 - '04 - F150 - Ford
I was able to install an original type door by cutting a hole in the box, but it was not easy to do and I don't recommend trying it with the one piece door unless you are fully prepared to break and replace the new door, the air box, and everything in it. I was working on my own truck, so it was all on me if I broke it.

The door is controlled by a servo motor called the blend door actuator, and as with all things electrical it can fail.
You can check the action of the blend door and blend door actuator by removing the cover between the transmission hump and lower dash. If your truck has a console, it is under and at the front of the console. There are pretty good video directions on the link above.

Or you could do a heater core bypass during the summer to keep engine heated coolant from circulating through the air box inside the cab.

 

without the AC working, you should get outside ambient air temp on the blue side and heater core air temp on the red end of the scale.........look closely at the motor operator on the door that Sam talks about. ....... lay on drivers floor and look up toward the radio.... taking some of the trim off gets better access for working.

 

Thank you for the feedback. After viewing the videos. I think the blend door can very well be my issue. I will dig into it soon and let you know what I find. What happened to the old days when access to things was easy. Here is a pic of the heater box on my 66 F100. Just a simple lever to manually move from heat to defrost !! and it comes out with just a couple of bolts Thanks again

 

GEES... that would be to simple. Why would you want to make it so ANYONE could fix it ? LOL

 

I always like to update everyone once a problem is resolved and thank everyone who offered suggestions. Great info on these forums. So I measured the voltage at the blend door actuator motor and had 12V present. I then measured resistance of the variable resister pins coming from the temp dial and saw the proper resistance on the hot side and cold side. With that info, I changed the motor and all is good. Here are some pics of the failed motor along with one of the schematics I used, Now on to the AC not working !Thanks everyone.

 

YEP...... after the smoke leaks out, they don't work so good !!