04, 2500. The **** that control the defrost, heater, and vent duct valves does not seem to work, only once in a while it seems. is it the **** or some thing els. it sucks that i need the defrost in the morning and only the vent works. no matter where the **** is at.

 

Sounds like a blend door issue to me.
Do a search on blend door and there's lots of posts about this all to common problem.
There are some work around repairs to this
Heater treater web site describes your problems. How to solve them and parts to do it.
http://www.heatertreater.net/indexiphone.html
Al.

 

I think Al nailed it. My 05 does the same thing. My remedy, other than ripping into it, is to set all up the day before for the next morning. Once the doors are set, they'll sit there until a move request is received from the computer.