[scaviola]

I had this problem a while back. Turns out that the A/C evaporator was clogged with tons of dirt and grime. Since it's the first thing ing the air flow path, it stopped all air from blowing, on all settings.
I cleaned it out by removing the blower and spraying some cleaner in the hole, then washing it out with a hose. You can't see the evaporator from the blower hole, but if you put your hand down in there you can feel the fins to see if they're clogged or dirty.