I have had this problem for a while now and I'm looking for help. The heater will not switch directing heat or a/c from the floor. It does direct some to the windshield but not really enough for our winters and not at all to the forward vents. I have changed the actuator and my mechanic told me that the blender door is sticking and needs to be cleaned or replaced. He said it is a expensive fix. I consider myself fairly handy and want to save a few bucks. I am looking for some help/instruction of how to access and fix this.

thx

 

Dash has to be removed. That is about the best I can do.

 

I did a quick search and found this post on how to install a new actuator on the blend door. Hopefully that will get you moving in the right direction.

2008 SD Blend Door Actuator Installation

 

Before you do anything, remember that the heating unit is vacuum controlled. If there is not sufficient vacuum to operate the system, it defaults to blowing out of the defrosters.

You may be tearing your dash apart for no reason.