Windshield Problems of Mercedes Benz SLK230

This is a report about unusual fogging up of all vehicle windows if the a/c is switched off while driving. This makes the car undriveable without a/c being on all the time or having to open windows due to lack of visibility through the windshield. If, for some reason, the a/c malfunctions while driving, this could pose a dangerous situation if people don't realize what happened quickly. This is very similar to what happens if one drives with the climate control on recycle instead of allowing fresh air in cold climate. But in this case, it is fogging up regardless of the temperature/humidity outside and even when the climate control is not on recycle mode. The car has a fresh/recirc flap inside the dashboard automatically controlled by a flap actuator. If this part fails, as I suspect it has happened, then the flap can get stuck in recirc mode which no fresh air will ever enter the car when windows are closed. Even if a/c is on to prevent fogging, driving with no fresh air coming in can be dangerous as carbon dioxide builds up inside from breathing leading to sleepiness in the driver (which is why driving for long with recirc air is not recommended). The problem is that this is a silent malfunction, and other than the fogging problem, there is no other indication. I have taken this to the dealer and they say they cannot reproduce the problem. But I can reliably reproduce this within 3 minutes of driving with a/c off. There is no recourse left for me to get this problem fixed and driving this way if there is no fresh air coming is dangerous to me and to others on the road.

See all problems of the 1999 Mercedes Benz SLK230 🔎.