Steamy Windows!

Thanks all for your ideas - i have removed the pollen filter completeley but still the same problem - i will check to make sure the drain is clear. The 'Rain x' stuff i reffered to is an antifog, this has helped but not solved the problem. I do get a funny smell from time to time through the air vents - smells a bit like grease! just an idea - could it be exhaust fumes in the cabin causing this? - the only reason i ask this is that it fogs over after the car has been running and then left for a bit - its never fogged over first thing in the morning. Any more ideas?

When my 855 T5 did the same, it was the Heater element that had gone. Presumably shotblasted the same way as the aircon evap. I took the plunge and got both replaced at the same time and then fitted a pollen filter holder and element. No snags with the heater since.