What is an Automotive Air Conditioning Expansion Valve?
2 Answers
The automotive air conditioning expansion valve mainly consists of three parts: the valve body, the temperature sensing bulb, and the balance tube. Its function is to throttle and reduce pressure, transforming the medium-temperature, high-pressure refrigerant liquid into low-temperature, low-pressure wet steam before the refrigerant enters the evaporator. The refrigerant then absorbs heat in the evaporator to achieve the cooling effect. Below is an introduction to related content: 1. The expansion valve controls the superheat of the gaseous refrigerant at the evaporator outlet to regulate the flow of gaseous refrigerant entering the evaporator. 2. In specialized air conditioning systems, due to the evaporator having multiple paths and using a showerhead-type liquid distributor, the pressure drop is relatively large, resulting in varying temperatures at the evaporator inlet and outlet. It is a component that transforms the refrigerant in the air conditioning pipeline from liquid to gaseous state. 3. Classification of automotive air conditioning expansion valves: Thermal expansion valves are divided into internally balanced and externally balanced types. Based on the balancing method, thermal expansion valves are categorized into internally balanced and externally balanced types, with the working principles of internally balanced and externally balanced expansion valves being fundamentally the same.
Speaking of the car's AC expansion valve, I personally think it's quite a core component—that little valve responsible for the AC's cooling function. To be specific, in the AC system, it's in charge of converting high-pressure liquid refrigerant into low-pressure gas, which is how it absorbs heat and cools the air inside the car. Normally, it's located in the engine bay, near the evaporator. If the expansion valve malfunctions, the AC might blow warm air or cause the evaporator to frost over, leading to fluctuating temperatures inside the car. I drive an older car and have experienced this issue before—the mechanic explained that a clogged expansion valve can disrupt cooling and needs immediate cleaning or replacement. For maintenance, it's recommended to get a full AC check-up every two years to prevent failures. After all, driving in summer without AC is unbearable due to the heat, and it could even affect driving safety.
