Heater stuck on defrost

I have a 2000 Dodge Ram Sport 1500 and the heater won't switch the air from defrost to any other position.

Does anyone know where I start to look to fix this problem? I'm sure the doors are probably vacuum operated.

-slacker

Well, I pulled the Dodge into the shop and reluctantly dug in and took most of the dash apart. I checked the back of the switch THEN I raised the hood and started tracing vacuum lines. :mad:

The black vacuum line that goes through the firewall with the A/C lines was almost rubbed in two. I just pulled it out as much as I could, cut the bad spot out and put a splice into it, and it's perfect once again! :biggrin:

Shoulda checked there before I pulled the dash apart. :screwy:

Simple! :smokin:

-slacker

Yeah check the vacuum lines on the right side of the intake plenum. The HVAC vacuum source gets "T" 'd there and goes through the firewall. With the engine running, check to see if the black vacuum line has vacuum at the HVAC control head. If it does, you'll need to replace the control head more than likely.