hi guys i have and 08 f-250 6.4 king ranch with auto climate contol i noticed that when i set my climate control to defrost it switches to the floor as well. it will come off the floor when i switch to vent and blow just on the floor when i switch to floor. obviously it comes out the floor and def when i select both. y would it come out the floor and def when i select def only? is this a programing issue?

thanks in advance

 

know one els has had this issue?

 

Your blend door actuator is going south. Mine does this as well and it also starts blowing hot air from the A/C vents sometimes. There is a thread on here about how to change it, but I've been too lazy to do mine yet.

 

If it is your blend doors...generally its the temperature that will not control. A vacuum signal controls where the air blows out from. If you have ESOF 4wd the hoses or seals are likely the culprit down at the front wheels. This usually causes a default setting to defrost.
The climate control option should have 2 servos to control 2 blend doors. I replaced mine and did a write up on it in the tech support page. Not sure if the technique applies to the auto climate controls? I think at least the passenger side servo may be the same but there is also one on the drivers side with your set up.
Dealer wanted $800 to do mine stating that the whole dash had to come out, really hummm, NOT! I did it for $32 plus 2 hours of my time. Most of that was discovering how to safely disconnect the air bag above the glove box and some basic exploring of how to remove various ginger bread dash parts which have no standard fasteners.