I have an 05 F250 and any time I put it in 4x4 the air conditioner goes to the defrost vents. Is this normal or do I have some sort of screwed up problem. I don't remember it always doing it and have not tried locking the hubs before switching it over.

 

Sounds like you have a vacum leak in the 4x4 system

 

I noticed one day mine does the same thing but im thinkin bout just puttin Warn manual locken hubs in.

 

Thnks for the idea of a leak in the 4x4 system I was thinking the same thing although if it is a leak then its not very bad. I first noticed it when I put my fifth wheel away and had to use it. The truck went in to 4x4 and back out just fine other than the defroster instead of regular vents. I have tried it since as well including today and no problems with the 4x4 other than if I put it in 4x4 with the switch while stoped it locks it in unlike before when I had to get out and lock the hubs if I was not moving. Any ideas of where to start the leack checks?

 

my 03 does the same thing. I have looked and looked for a leak. It will however go back on the the dash vents if it in normal air and not max as about 2 mins.