The EATC was replaced in my truck about 7 years ago. The symptom at the time was the system would appear to be on when it was shut off. Most of the time you would feel hot air coming from the floor ducts when the system was off.

Right now all the air, no matter what temperature, comes out of the defrosters. I can change the temperature, so I believe that the blend door is functioning correctly. I have run the diagnostic test on the head unit and there is no code after the test. I have good vacuum up to the back of the head unit and I have also done the O ring fix mentioned on several blogs. Periodically the system will seem like it turns itself on, cause you can feel warm air while the system is off, much like it was 7 years ago. At this point I'm leaning towards having another bad head unit, but I need to know if there is any test I can do on the door that directs air to the different ducts.

Thanks for reading and any help is greatly appreciated.

02 F150 Super Crew Lariat FX4 White & Silver
5.4 /w Roush Cold Air Intake & K&N filter
3.55 LS
MagnaFlow Cat Back
MagnaFlow Hi flow Cats
JBA Silver Cat4ward Headers
Rancho RS9000XL's
Rancho Steering Stablizer
Hellwig Rear Anti Sway Bar
Lightning Tails
Outland Sport Bumper Guard
Hella 550's
Silverstars
Superchips 9100 Micro Tuner c/o Troyer Performance
Underdrive Pullies c/o Troyer Performance
Mag-Hytec Trans Pan