I was thinking it is very likley that it was something the tech may have done, however I am living out of town about 2 hours from the installer, so I was trying to figure out if it was something simple I could fix, rather than waiting for my next trip home. I will investigate into what you said...
I'm having a very similar problem on my 2000 Taurus SE...the A/C will only blow on the windshield and under the dash. I tried the above but none of it seems to be the cause. I did recently have a new cd player installed, could this be causing a problem?