I have a 2001 F-250 Super Duty that has just started to have a problem with the air conditioning. When I switch the air to the max setting the majority of the air is diverted to the passenger vents, any ideas why or what to check?

 

Maybe the vents are closed. On my 2001 f250 you have the option to close the vent entirely on the face of the vent itself. One controls direction, the other controls volume.

 

I don't think it has anything to do with the vents because the air comes out fine on the a/c setting and as soon as you go to the max the output changes.