I have a 2000 Blazer LT 4WD 4D and there is always heat coming out of the vents. I replaced the Computer Climate Control module and then the AC worked. At least until the engine warmed up and the air got hot once again. I can change the fan speed and which vents the air comes out, but it is always hot. I wonder if there is something constantly directing the air around the engine that is not closing. Anyone seen this before?