First check whether the coolant is sufficient. If the coolant is missing, the air conditioner will not heat.
You also need to check whether the cooling fan is working normally. If the cooling fan is running constantly, the water temperature cannot rise and the air conditioner does not heat.
A clogged or leaking heater water tank can also cause no heating.
According to the type of heat source, automobile heating systems are mainly divided into two types: one uses engine coolant as the heat source (currently used by most vehicles), and the other uses fuel as the heat source. (Adopted by a few mid- to high-end cars). When the engine coolant temperature is high, the coolant flows through the heat exchanger in the heater system (generally called the small heater water tank), and heat exchanges between the air sent by the blower and the engine coolant. The air is heated by the blower It is sent into the car through each air outlet.