Feel free to move whereevr this belongs, but I did not see anything in the public forums that this fit into.

2005 computer climate control. On a recent trip I found that the passengers side HVAC was blowing warm air when on AC. Drivers side was just fine. Messed around quite a bit with the Tech 2 etc and no luck. No codes etc. Finally we switched drivers and I played with the Tech 2 on the road. Found DTC 418 if memory serves. Reset and it worked for a minute then quit. Repeated 3 or 4 times and then it finally went and has been fine ever since.

During this ordeal I called White Truck from the forums here. By the time he was free to call back I had it working, but ironically he fixed one for the same thing the very same day. Further to this I had a customer who I had just done a tune for (from WI) who also had the same issue which magically fixed itself.

What I learned from White Truck:

"With this issue, the actuator is disabled for the remainder of the ignition cycle, even if the intermittent cause is no longer present. That is why clearing the code can get it to resume operation, as long as the condition causing it is not there at that time.
As I mentioned, this is a fairly common problem. I usually find poor terminal tension at the actuator, or at the connectors on the right end of the dash. The actuator itself can be the problem too. There is a potentiometer inside that if it has poor contacts, will cause the same concern. Rarely have I ever seen a problem with the connections at the control head or the head itself.
There is also a calibration update that corrects for an actuator over travel concern that causes the feedback value to be outside of the learned values."



To further this he also suggested that if it became intermittent I should try to get to the desired AC position and then unplug the actuator which would leave it parked in a fixed cool position.


I think the fact that this occurred in 3 in WI trucks on the same timeline shows a common issue no doubt. I know that I have seen the programming update, and think I may have loaded it, but may be mistaken.