Climate Control Issue

I have a '06 LBZ CC SB with the dual zone climate control. I have noticed several times in cold weather (I live in Georgia so I know cold to me means different numbers than a lot of you) in the mid-low 20's while on the highway for extended period of time, the temp in the cab climbs to the point I have to continually lower the temp setting to stay comfortable. Last night I started out in Atlanta (30 degrees) with the control set on 72 degrees. Within the first hour I had reduced it to 68 degrees to stay comfortable (this was all at night so the sun shining through the glass wasn't an issue). Over the next hour or two I had turned it down to 64 (the outside temp had decreased to 19 at this point). Any ideas what this might be? I'm beginning to feel my first trip to the dealer for a bit of warranty. All else with this truck is superb and I now have 14,000 miles on it. Thanks for any thoughts. Ed

Are you running on defrost? Have you selected Auto or are you manually selecting items? If you override anything like fan or vent position, I believe it goes to partial manual mode.

Recirc turned on? That way you wouldn't be gettinfg any fresh air in.

Mine, once warmed up, has been pretty good at mainataining cab temps without need for adjustment.

Is you AC working? Meaning, if you turn temps down a ways, do you get a real blast of cold air?

I had it in manual mode, no a/c, bi-level, recirc was NOT turned on so I was getting outside air and the a/c does work well when turned on. Today coming back home the outside temp was in the high 30's and it did the same thing. When set to 70 it got too hot after about an hour. I kept turning it down by a couple of degrees at a time and it would be comfortable for a few minutes and then slowly get too hot again. Finally at about 64 it would be comfortable and maintain the temp. Strange.

Try it on full auto. I think you'll be surprised how well it works.

In manual if I understand correctly it functions like a regular HVAC system and does not adjust itself.

Thunderbirds had a rare problem like this. The blend door was not working properly. It would either stick or was not moving in porportion to the controls. There's a slim possibility you may have a similar problem. Since a computer has control over the door position, there is a position sensor on the mechanism to tell the computer where the door is. I don't know about this particular system, but the Tbirds used vacuum servos on the blend door. Low vacuum or a tight mechanism or a not properly calibrated sensor would cause a problem similar to this as the door would not properly proportion the amount of heated air versus not heated air. Granted, this is stretching it a bit, but it is a possibility. I just tipped 5400 miles on my LT3 and my climate control is ok. I've had no problems on the auto setting either. Even on manual it seems to maintain a good setting.

My 06 up here in PA had the opposite prob. but I started pressing the auto button after each start up and that has squared the problem away.

Once I set mine on auto it stays on auto until I press a different button regardless of how many times I start it. Mine works awesome on the auto setting. Set it and forget it.