Fellas I have a 2005 Silverado 1500 with a 4.8. When I turn on my air it starts out blowing cold then turns to heat. The heat only comes out the driver side vents and it still blows cols air out the passenger vents. I have to shut my truck off and turn it back on to make it stop. Is there a sensor or vent thats goen bad that I need to replace. Any help in this matter would be greatly appreciated.