Chevrolet Repair: heater problem, 2003 chevy silverado, chevy silverado

Question
I have a 2003 Chevy Silverado and my problem is with the heater. I have an electronic dual zone control and when put it at 32 degrees I get hot air but as soon as I go to 31 degrees or less I get cold air. The mechanics have been looking in to my problem but they dont find the problem.

Answer
HI JACQUES,WE HAVE SOME PROBLEMS WITH THE CONTROL HEAD ITSELF. THIS IS WHERE YOU ADJUST THE  TEMPERATURE ON THE DASH..I HAD THE SAME PROBLEM ON MY 2004 SILVERADO..[DUAL ZONE] AS WELL.THE ONLY OTHER PROBLEM IT COULD BE IS A BLEND DOOR IS STICKING UNDER THE DASH OR THE SOLENOID THAT CONTROLS THIS DOOR IS GOING BAD...THIS WOULD REALLY NEED TO HAVE HANDS ON TO REALLY SEE WHAT IS GOING ON HERE. BUT HAVE THEM CK THE ABOVE..HOPE THIS HELPS YOU,,TOM...