Heater unit taken from the engine bay. Heater matrix removed. Fresh air comes in from the top via the ventilation flap in front of the windscreen. The handles on the lower part of the dashboard are connnected to the small vertical flaps that are visible left and right of the grid (metal flap with a 90 deg. bend.). They either guide the fresh air through the grid and thus through the heater matrix in front of it, or open a bypass channel on each side. The air leaves the unit via the sides where the electric motors are.