hi, i'm new to this site. i have a 95 k-1500 4x4 and hope someone might be able to help me with a problem on my truck. question is, no matter where the setting is on the heater or a/c, air always blows out the defroster. the control does work and will switch from the floor, vents, and defrost. air will blow out from the selected vent, but blows from the defroster as well, like 50/50. not good when your feet are cold or when using the a/c. any ideas?