If there is no heating, first check whether the thermostat is damaged and turned on normally, or remove the thermostat in summer and forget to install it in winter.
Detection method: start the car to refuel, and see if the water thermometer reaches the red scale line and automatically drops. If so, the thermostat is working normally; If the water thermometer keeps at a certain scale (only rises by one or three squares, provided that the water thermometer is good), open the water tank cover (don't open it when the temperature is high, so as to avoid scalding). Look at the speed of the water flow when refueling, and refuel instantly. The water flow is very fast, indicating that the thermostat is faulty and can be replaced; If the flow rate is slow or the reaction is small, remove it as follows.
If the heater has been used for more than two years, it is suggested that the heater be removed and the small water tank (referred to as the closed water tank) in the heater be cleaned externally to see if there is any irregular collapse (treated with a saw blade), which causes the air flow of the heater to blow on the water tank, and the wind force becomes smaller, so that the heat and wind force cannot be fully exerted. If you feel the wind is strong, blow the inside of the water tank of the heater with an air pump to see the wind force at the air inlet and outlet. If the wind is similar, there is no need to change the water tank. If the wind is different, a new water tank needs to be replaced.