1998 S70 turbo AC overheating?

[Racemaster33]

I have a 1998 Volvo S70 turbo that has started something strange. I can get in the car, turn the air on and start driving, after a period of time the air quits coming out of the vents. the AC is still blowing and it cold, but the flapper seems to be shut off. No matter what selection I choose on the climate system the air still won't come out. You can hear the fan blowing hard but something has shut the air off to the any/all vents. My first guess is that it's either the control head or the selector motor that moves the flapper from one location to the next. I have no idea where to find this motor or how to test for either problem. I'm looking for some great wisdom on this one. My car is black and I'm being baked inside.