Changeover valve. HVAC Heater Control Valve.
A valve used to Control the flow of engine coolant to the Heater core.
Fits 335d
Heater Control Valve - Repair or Replace
A heater control valve diverts hot water (coolant, or antifreeze) from the radiator into the heater core in your vehicle’s cabin, resulting in soothing warm air. If your heat has stopped working, your may require a replacement heater control valve.