02 suburban climate control problems!!

[Jebenubin]

Ok gents (and ladies), I have an 02 Chev suburban with the 8.1 and I'm having issues with the climate control. If the outside temp is 40 or less any setting on the dial above straight cold blows max heat. Its super annoying driving more than a few miles as I'm constantly having to switch from cold to 66 (and getting piping hot air) to try and keep the cabin temp comfortable. I know that a control module in the rear has failed and it has "defaulted" to cold only, but that should not be the case with the front controls. I'm wondering if the temp sensor in the cabin has gone bad or what? Any help or info on this would be greatly appreciated!

[gmclowsierra]

is it auto or manual climate control?