Well, I got into my 1988 caddy today to drive home from work and the windows were fogges up. I turned on the defrost for the front windshield and off I went. As I drove I saw the windshield get even foggier. and when I put my hand up to the slots on the dash I could feel that there was no air coming out. Upon further investigation I found that the only place that air will bloww from is down by my feet no matter what setting I put it on ie; air, heat, defrost. I pounded on the dash hoping that I could get the airways opened, but no luck. I have heard of some cars not blowing air due to a bad vacuum, but to be honest I don't know exactly what that means or how to check it. What could the problem be? Any ideas or suggestions?