I have an 03, 2500 Ram, Cummins Diesel, 4WD automatic.
The HVAC control for the temp seems to only switch from extreme hot to extreme cold. I have removed the glove box and most of my dash and watched as the servo/actuator thing moved steadily from one extreme to the other as I slowly adjusted the temp control dial. I even moved the dial one 'click' at a time and watched the servo/actuator thing stop at each graduation as I stopped moving the control dial. Unfortunately, none of this seems to do anything to actually modify the air temp coming from the vents. Sometimes it is just cold, sometimes just hot, and sometimes just barely warm, but regardless of what comes out of the vents, it stays at that temp for the duration of my drive. It is different for just about each trip I take, sometimes it is hot, sometimes cold... you get the idea. Anyways, I have visually verified that the motorized servo/actuator thing does work in conjunction with turning the temp control dial (works with the fan on as well as off). Is there something inside the box that is likely to be broken? Can anyone point me to an online resource or exploded view of the HVAC box that could give me an inside view before I try to take the whole thing apart myself? Is this a common issue with the 3rd Generation Ram trucks?
Thanks to all in advance.

 

The blend door that gets moved by those servos is probably broken or stuck. Blend door issues are the #1 HVAC issue with Rams.