i just bought a 05 gxp with only 8k on it.... BEAUTIFUL CAR!!!!! I started the car to move it in the drive way and the climate control was working.... the next morning I was leaving for work and the screen was out and I had no control... just blows hot air.... first though the front vents then switches to the floor/windshield and stays there.... thank-goodness is winter time!!

I dought a fuse is it so It will be a loose wire/connector or a bulb burned out or the whole control unit may have to be replaced. But since you say its working i believe it would be a loose wire for the backlight if thats not the case you might have to get it checked at a dealership.

Fist step would be check the fuses. Not something common here for sure.