the heater in the blazer was wokring fine and all of a sudden I only am getting cold air. The blower works, it's pumping air, it's just COLD. Also with the heat/air controls on off if I move the switch to hot it takes a long time to get any warm air in, If it gets any. I don't know if it's realted, because I think I'm just out of freon, but the AC isn't blowing as cold as it should. But like I said I think I'm out of freon. I've check fuses, and all the connections on the heater and can't find anything. What could cause the blower to still be fine but I'm not getting any heat out of it?