Originally Posted by bdodge445
Correct me if I am wrong, but I don't believe these trucks have a heater control valve. I would lean towards a faulty t-stat even though it is new, I have had them bad right out of the box as well. I would also suggest replacing it with a 195 degree t-stat like it should have, the lower temp will tell the computer that it's cold outside and waste fuel.
Well if there isn't some sort of a valve the engine may actually never reach temperature because of the heater core cooling the coolant prematurely.