The car air-conditioning heater is the main heating system in the car when the car is running in winter. The whole device can transport fresh air or liquid medium to the heat exchanger to complete the whole process of absorbing heat from the heat source, thereby increasing the temperature of the air and liquid medium, and supplying hot air to passengers for heating, window glass defrosting and The air in the car is adjusted to meet the requirements of comfort and stability. At present, there are many classifications of automotive air conditioning heating systems in the automotive industry. If they are divided according to the heat source used, they can be divided into non-independent heating systems and independent heating systems. Non-independent is also called waste heat system. The water-heated heating system is widely used. Its working principle is to use the waste heat of the cooling circulating water of the engine as a heat source, introduce it into the heater, which is also a heat exchanger, and then the air in the cabin or the air outside the car is blown by the blower. The air is heated to make it warm, and the heated air is blown to the people in the car from different air outlets under the action of the blower. At the same time, warm air is blown out through the air outlet under the windshield glass, which can keep the inner temperature above the fog point to prevent fogging or frosting. The car air-conditioning heater continues to bring warmth to the passengers throughout the cold winter. Whether it can operate normally directly affects the sensory experience of the passengers, so its quality has a great impact on its normal operation.