2000 ram 3500 4x4 cummins turbo. Temp. control is stuck in cold position on either a/c or vents. can go from a/c to vent but nothing happens when i turn temp. control **** from cold to hot. looked at fuse box under the hood an saw a open spot for a relay that said (02 front heater). I don't recall ever seeing a relay in that slot and know I never removed one. Any and all opinions will be greatly appreciated.

 

unsure about a 2000 but 0n a 98/99 it is cable actuated, sounds like a broken/unsecured cable......from dash control to top of core/evap unit might have to pull dash (2 hours with cheats) check the back of dash control first.

 

Pulled dash control and found only a plug with 3 wires going to it. Unplugged it to make sure wires were OK, all looked good no loose wires. thanks for your help!

 

aren't they vacuum controlled on those?

I forget. I had an 01, but never had to work on it

 

Check if the **** is cracked on the back and just spinning on the shaft.
It can feel just like it's turning but it's not.

 

Thanks for the advice, I will try anything. It's getting colder so air cond. or cold vent not welcomed much.