I experienced the full fog over Friday while driving in foggy conditions near 32 degrees. PMCErnie, I can assure you I used the defrost button and it didn't help one bit. The problem was that the HVAC wouldn't allow me to recirc the air with the AC on. It insisted on bringing in outside air and that brought the moisture with it. If I set my temp to "low", and used windshield and foot well vents, I could manually set the fans to max and that got me going until I started freezing. When I was forced to the side of the road again, I eventually turned off the auto recirc and left the rest in auto and it didn't happen anymore. Coincidence? Who knows.