Digital Climate Control problem in '05 2500HD Duramax

[Outfitter17]

I have a 2005 2500HD Duramax with digital climate control and I have noticed that I only have heat when the dial is set to 90 degrees. As soon as I turn it down even only to 89 it blows out cold air? Everything seemed to work fine in the summer controling the temps, but with the cold weather something must have went haywire? Has anyone experianced this before?

[Outfitter17]

TTT

[Scott K]

Does this have dual temp control? Where you can adjust passenger and driver side sepperately? If so, and both sides adjust cold, it looks as though you may have a bad control head. If it is singe temp control and can be the control head or the blend door motor/actuator.

[Jeremy airjer W]

With the key on, engine off, and blower on the lowest setting see if you can hear the blend door essentially moving a lot. There will be a noticeable tone difference between full hot and full cold. you may have to play around with the fan settings to hear it). If you hear and extreme difference in tone as you switch between the two temp settings tan I would be more inclined to focus on the control head as well.

[Outfitter17]

It does have the dual climate control where you can set both sides different, but with defrost on both sides are the same temp and when I go from 90 to 89 it goes from hot to cold instantly.

I will try you test airjer with the truck of thanks for the help.

[Outfitter17]

I took it into a GM garage in Green Bay, WI this morning and they said it was a sensor above the driver? They said the sensor thought the truck was 131 degrees F all the time. It kicked out heat at 90F because I was calling for max heat, but when I went below even to just 89F it would send cold air trying to get from 131 to 89. The part was cheap and it was a quick fix and so far so good.

They said its only the 2nd one they have seen fail since the digital climate control came out.

[Scott K]

That does make sense!