I have a 2004 FX4 SC. LAtely I have been having issues when I go to change the location of the venting. Air is always bloing out the main front vents, yet won't switch when I want to go to defrost or floor vents only.

Are they vaccuum driven ? Where are the vaccuum lines on a 2004 SC ?

I have looked in the HVAC section for a location of these lines. No luck. Thanks.

 

I had this same problem with my previous superduty. It was vaccuum operated. The truck was still under warranty and they replaced a solenoid, I think....problem solved.

 

Balance.... checking!

 

Can someone shoot me a quickie picture on what lines I should be looking for looks like. I looked behind the battery and the only thing that I see is the PCM with a crap load of wires coming out ...

 

I have the same problem. I think it is a new system design. some say it hangs up on something.
Josh