Near the engine, usually in the engine room, there are two pipes about the same size behind the middle. When you see those two water pipes, you will find the water valve.
The heater switch has a hot and cold switch on the central control panel of the bridge, with one side red and the other blue. Just pull the switch to the red side and turn on the blower switch. After the engine temperature rises, warm air will naturally come out. If the heater does not come out, first check whether the thermostat is damaged and it is in a normally open state, or remove the thermostat in summer.
If the heater has been used for more than two years, it is recommended to disassemble the heater and clean the outside of the small water tank in the heater.