Have 07 silverado new body style, with dual climate control have promblems with heat on controls when I set digtal control to 80 degrees seems cool, not like a/c cool ,when put up 90 degrees blows hot which is great,but anywhere between 70degrees,and 85 degrees seems cool.i thought that was the whole purpose of climate,control was to control settings. Does any one a have and idea what can be the promblem truck has 32000 miles on it.