How to Determine if the Expansion Valve is Malfunctioning?
2 Answers
Common failures of the expansion valve include blockages, which can be measured and diagnosed using a pressure gauge. Below are detailed explanations of the expansion valve: 1. Expansion valve blockage. When the car's air conditioning is turned on, it may fail to cool, and measuring the pressure in the air conditioning lines with a pressure gauge will reveal excessively high high pressure and excessively low low pressure, indicating a faulty expansion valve. 2. Symptoms of a damaged expansion valve include the low-pressure pipe not being cold to the touch, frosting on the dryer and condenser, abnormal high and low pressures, and abnormal temperature in the high-pressure pipe. 3. The expansion valve is a crucial component in the refrigeration system, typically installed between the liquid reservoir and the evaporator. It functions as a throttle, converting high-temperature, high-pressure liquid refrigerant into low-temperature, low-pressure mist-like hydraulic refrigerant through its throttle orifice, creating conditions for the refrigerant to evaporate.
When the car's expansion valve malfunctions, the symptoms are quite noticeable: I turned on the air conditioning and found that the cooling effect dropped significantly, with weak cold air or even hot air blowing inside the car—this is a key sign. A clogged expansion valve can obstruct refrigerant flow, potentially causing the evaporator to freeze and block the air vents. During inspection, abnormal pressure in the high and low-pressure pipes can be observed: the high-pressure pipe feels scalding hot while the low-pressure pipe is icy cold, yet the cooling output remains poor. A faulty expansion valve may also produce a buzzing or hissing sound due to refrigerant leakage. Additionally, expansion valve issues are often caused by contaminants in the system or insufficient refrigerant levels. It's recommended to use a professional pressure gauge to test for significant pressure differences or system leaks. Repairing an expansion valve is not straightforward, so it's best to have a repair shop conduct a thorough diagnosis to avoid damaging the compressor. Regular air conditioning maintenance can prevent such problems by ensuring the expansion valve stays clean and unobstructed.
