I have an 09 reg Subaru Legacy Boxer Diesel Estate. From new, every Winter, I get really bad condensation inside the vehicle. Last Winter, I had to de-ice the inside of the vehicle before I could drive it. It has been back to Subaru, Tunbridge Wells, twice and they can't find anything wrong. Would you please have any idea what could be causing this problem as it starts appearing every November and continues until the better weather comes along. I do use the air con most of the time when driving. If it helps, when I turn off the engine there is a sushing noise from under the bonnet, similar to air escaping under pressure!
Many thanks for any advice.