I had an old 1979 Blazer (back in 1981 & 82 & I remember it blowing lots of cold air. I now have a 1989 Blazer and it doesn't blow much air through the vents at all. The fan is good & turning at the proper speed and direction. The air that it blows is cold. The problem is that there isn't enough air getting out of the vents. Anyone have any expereince with this?