Exactly MAYA...that's what I found (by mistake) I had the Vent selector set to the defrost mode (12 o'clock) with the ac running. If you put the selector to vent down (at your feet) it will reduce or eliminate the fogging.

Also, I'm going to buy some RainX (interior) to coat the windows when the weather changes in the fall. This will also help with "fogging" issues. NOTE: this is not the same as regular RainX, which you use on the exterior side of the windows.