Hey on my '03 Cavalier the center vent blows very little/no air, it doesn't matter what setting its on (feet/head), it will not blow out any air. Whats involved in fixing this?

The foam layer on the mode door has come off and it blocks everything. Take the topdash pad off. When you remove the duct from the main vent, you'll see your problem. You can get a replacement piece of foam from the dealer, or just get something similar and cut to fit and glue it to the door (this prevents air leaks). Also check your mode select cable. You can see it from the floor on the passenger side best. This foam sometimes causes the cable to bind and kink. If it is kinked, you should replace it.