I have a 1995 Cavalier. This is the problem: When the a/c is on, and only when the a/c is on (it does not do this when the heater is on), if the blower selector is moved from the highest setting, almost no air will come out of the vents. All the speeds still work, but the air does not move. The little air that does come out is still ice cold and the vent selector will still change where the air comes out. Every once in awhile when this happens, a fog or mist will come out of the vents. It is not a bad heater core; this has been checked. The mist has no odor and is not sticky. If the car is shut off and left for awhile, when it is re-started everything will be normal. I have no idea what this could be and everyone I ask is stumped. Any ideas? Thanks in advance.

Im assuming you talking about the actual selector as to where the air comes from. IE: defrost, vents, floor, and so on. Basically what it sounds like is you have a vacuum leak in the system causing it to not change. But when left off for a while, and then turned back on, it works. The leak could be after the selector and just not letting the doors move. Idk but its just a guess, but I would start seeing if the door actually moves. When the ac is on, it has a heavier load on the engine, so it dont sound out of the water. I would start there.