I'm a newbie here - first post and I wasn't sure whether to post here or in engine section. I've a 1996 C200 sedan, and just recently the dash vents have given over to producing hot air only. Very useful when we are on the cusp of Summer here in the Antipodes!!! I've done some general research on the web, noting comments about 'vaccuum lines behind the glovebox' and also references to the 'heater control valve' in the engine bay, but its all a bit too general for me to really glean anything substantive. The only bit of additional info. I can provide is that I was driving the car one hot day recently, so I put the AC on. A short time later a noticable - but not overpowering - smell came into the cabin, which I would best describe as like the smell of steam, and which remained for the rest of the 45min journey. The temp gauge went up a little for a while, but not unusual for the hot conditions outside and the verrry slow traffic I was caught in at the time....it returned to normal when I broke out of the traffic. No change to the water level in the reservoir tank either. From that time on I've been getting the hot air...doesn't matter what I do with either of the roller temp selectors. Any clues where I should start looking? (I live in a semi-rural area with no Benz shops around...I'd like to understand the nature of my problem before sending it to a workshop) Thanks in anticipation!