just bought my 2006 6.0 f-250 powerstroke 3 months ago everything was working great,had the ac on and the vents stopped blowing air and now only the defrost is blowing air,never owned a diesel b4 and looking in the engine bay of this truck is like looking at an import 2 me it is jam packed!!
so I have no idea where 2 start.also I'm looking 2 add some power, turbo seems like it takes a while 2 spool up?so may want 2 replace? and looking for recommendations on a tuner

 

I would check to make sure your switch is working properly. I would use an ohm meter to check resistance to the switch itself, if you have high resistance you could have electrical issues such as a wire that's fraying out, bad connector, ect. Check for proper voltage. If you determine the switch is still good I would check the actuator that's opens and closes the vent channels.

But as for your tuner I would go with and SCT. In my opinion on a 6.0 you can't go wrong with them. But first you should bullet proof it. You will regret it if you start hotrodin it without bullet proofing it.

 

My 2005 did the same thing ... theres a little air pump on the passenger side on top of the wheel well... Mine went out and did the same thing... Swapped mine with a buddys just to check and that was it.