I done a service on my mates dads W202 P reg over the weekend. I changed the cabin filter as there was bearly any air being blowen into the car from the heaters. Must have never been changed However, the heaters blow out hot air when the car is moving but as you come to a stop they blow out cold air, without touching any switches so they are still set to hot. It was doing the same thing before i changed the cabin filter. Anyone experienced anything like this before?