2. Set the blower direction switch to position
or 
.
The A170 Turbodiesel vehicles are equipped with a coolant heater, which enables faster heating of the passenger compartment.
The heater turns on and off automatically depending on the coolant temperature and the ambient air temperature.
If the engine has not reached operating temperature, then after it is turned off, the fan may start to operate spontaneously, and a small amount of steam and condensate may come out from under the bottom.
(Read more on the website www.mercedesman.ru)