What are the symptoms of a faulty car air conditioning expansion valve?

[BenjaminDella]

Car air conditioning expansion valve failure symptoms: 1. Low-pressure pipe not cold to touch; 2. Dryer bottle or condenser frosting; 3. No hissing sound heard at expansion valve or condenser; 4. Abnormal high and low pressure; 5. Abnormal high-pressure pipe temperature. The car air conditioning expansion valve mainly consists of three parts: valve body, temperature sensing bulb, and equalizer tube. Function of car air conditioning expansion valve: The expansion valve serves as a throttling and pressure-reducing device. When high-pressure refrigerant liquid condensed by the condenser passes through the throttle valve, its flow is restricted causing pressure drop, which leads to partial vaporization of the refrigerant liquid while absorbing latent heat of vaporization. This process lowers its own temperature accordingly, transforming it into low-temperature, low-pressure wet steam that then enters the evaporator to absorb heat from indoor air and continue vaporizing.