Check your OVP, take it apart and see if any solder is breaking apart on it. My car was having some electronic issues before and it turned out to be a faulty OVP, and when i took the old one apart, the solder was breaking apart and the car worked fine after I repaired the solder on the board. It doesn't hurt to check it out and attempt repair on it. Also figure out which relay controls the unit and make sure that's fine also. I think the climate unit it fine, as it wouldn't work at all if it were dead, i think you have a relay or electric issue.

__________________
My Cars
Mercedes CLS
Mercedes C-Class W203 - All time favorite

R.I.P.
Mercedes C-Class - W202 Lemon
Mercedes ML - Warrior
VW Jetta – Worst Car I ever owned - Alot of problems