HVAC issues

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.

John, this is ironic in the extreme. My Sierra has been stuck in the same scenario since I picked it up on Thursday from the injector replacement. Heat on the right, and cold on the left, with NO air flow out the dash (face) vents on either side, only the defrost vents. No amount of fiddling with the controls will change anything. I haven't pulled codes, so I don't know if I can clear it up that way. I have the Helm manuals, here at home, so I'll be looking into this thing. DTC 418, you say, eh?

Well, I hooked up my Hypertek, this morning and pulled and cleared codes. There were three. U1024 - U1041 - P0101 I didn't look up the code IDs, just cleared everything and went to stock tuning and the correct tire size for 265's.
Getting ready to put the Edge back in. I missed the power, coming up from S. NY on Friday.
Anyhow, we now have AC and heat, back where it's supposed to be. Hope it stays. Glad you put this thread in here. Thanks.:)

I've been reading about a lot of guys replacing the position sensors, but I seriously doubt that they are realluy bad.

I am hoping to get the time to do the factory update to the HVAC module programming soon. It has to do with the door going too far and creating this condition.

With computer climate I seldom jack it all the way, but I do see people turning to lowest temp in summer and hottest temp in winter rather than allowing it to regulate a nice steady temp as designed...

Hey Guys,

I was just wondering if a regular OBD II Code Reader would allow me to cancel this code and get my A/C working properly again? Or do I need to take it in to the dealer (Mucho $ for not much work). I have the same problem but I get the heat on the driver's side when it's supposed to be cold. The dealer "reprogramed" my computer and it worked for about 2 days then started pumping out heat again. What was the error code again? Thanks for your help.

Rod

So I bought a OBDII code reader, Just wondering if you knew what the code number was for sure?

Thanks,

Rod

This sounds like what my wife's 2005 Suburban is doing now. Has there been a fix determined for this yet?

Matt

Yep, they had to replace the left "door" of the HVAC. It cost about $800. I hope this isn't your wife's Sub's problem.
Good luck,

Rod

"but I do see people turning to lowest temp in summer and hottest temp in winter rather than allowing it to regulate a nice steady temp as designed..."

John, Don't you know these systems heat and cool better when this is done? I used to tell my wife, now ex-wife, that the a/c at home didn't cool any better when she turned the thermostat down to 50 something. I lost that battle.