Lately, I have no air coming from any of the 4 vents. I have an S 2003 model. They were working a few weeks ago. I tried different fan settings. Air is coming from the windshield vent, for the defrost cycle. The heat does work because the car does get warm.

 

hmmm... i have no clue...
Maybe check your cabin filter? maybe something somehow got lodged into it, stuck to it...

 

have you checked the blower motor. sorry i'm late to this but i just joined as a member and i live close to Philly so i thought i would check to see for anything in the area. hope this helps.