What are the symptoms of a clogged car AC expansion valve?
2 Answers
When the car AC expansion valve is clogged, it can cause the air conditioning to produce cool air but with no airflow. The expansion valve is a crucial component of the car's cooling system, typically installed between the liquid receiver and the evaporator. The expansion valve allows medium-temperature, high-pressure liquid refrigerant to pass through and become low-temperature, low-pressure wet vapor for cooling purposes. It controls the valve flow based on temperature changes at the end of the evaporator, preventing insufficient utilization of the evaporator's surface area and knocking phenomena. The expansion valve has two main functions: throttling and controlling the refrigerant flow rate. Based on the balance method, expansion valves can be categorized into internal balance and external balance types. In a car's refrigeration system, the expansion valve is one of the four major components, alongside the compressor, condenser, and evaporator.
Over the years of running my repair shop, expansion valve clogging has been a common air conditioning issue. The most noticeable symptom for car owners is that the air blowing from the vents isn't cold, even when the temperature is set to the lowest. Sometimes, you can even hear a hissing noise from the AC system, especially when the compressor kicks in. From a more professional perspective, the low-pressure line will frost over and turn white, just like the pipes in a freezer. If left clogged for too long, even the compressor oil can flow back into the condenser, causing more damage to the system. Once, I encountered a car owner who insisted on driving with the issue, and it ended up seizing the compressor, resulting in much higher repair costs. I recommend checking key components like the expansion valve and receiver-drier as soon as you notice any cooling abnormalities.
