My dad has an 04 5.4 F-150 around 32 or 33k miles, original owner. He has the air conditioner w/ the 3 *****, & 2 buttons, 1 turns ac on or off and the other controls if the air is circulating or coming from outside. The buttons have a little LED light on them. Recently when the ac is in the max ac position. The button that controls if the air is circulating or coming from outside will just randomly switch from inside to outside. And in the MAX A/C position it should only be coming from inside. It does not appear to be related to driving style (it doesn't happen just when braking or just at WOT) it seems completely random. Just wonderin before he takes it in to get it checked out (under warranty) if ya'll know what it may be?
Thanks

 

Just to clarify - is the mode door actually switching from fresh to recirculate or is it just the light on the button going on and off?

Either way, I'd be tempted to say it is a loose connection or bad switch since the issue is intermittent.

 

Yes sorry, the light on the button is displaying what is actually happening. When its in MAX AC & its circulating the air its blowin it as hard as it can and making it as cold as possible. But then the light will go out and the air slows down and warms up a tad, where it is bringing in air from the outside. All while the selector **** is still on the MAX AC position.
Is the door that controls the airs path vacuum controlled or electronically controlled?