Where is the heater water valve of Mercedes-Benz glc260?

Inside the engine compartment. The working principle of the car heater is that the radiator in the heater is connected to the engine circulating water through the inlet/outlet pipe. The water valve is a switch. The Mercedes-Benz glc260 heater water valve is in the left front direction of the cab, in the engine compartment, and is controlled by the air conditioning control panel. Control, the switch of the heater valve is electric.