I have an '04 HSE with 78k. The AC is ice cold. If I have the fan on more than one or two notches it blasts great and ice cold for a few miles. Then the amount of air coming into the cabin is greatly reduced. The fan strength and speed seem fine, AC is still cold. Its almost as if there is some type of flap in the dash that is shutting itself. Yes, I do have the hot/cold dial spun to full cold at all times. Ideas?