What Causes Car AC Pipe Freezing and No Cooling?
3 Answers
Car AC expansion valve freezing and no cooling is a refrigerant system icing phenomenon. The specific causes may include the following: The expansion valve's adjustment is too small, resulting in excessively low low-pressure. Insufficient refrigerant in the system causes low evaporation pressure. Clogged interior circulation filter. Malfunctioning thermostat (or temperature sensor) prevents compressor shutdown. Failure of the variable displacement compressor's energy control valve (pressure regulator) keeps the compressor operating at full capacity, causing excessively low pressure and evaporator frosting. Moisture in the refrigerant freezes at low temperatures, forming ice plugs that block capillary tubes. Once capillary tubes are blocked, the refrigeration system cannot cool.
I've driven many cars, and it's quite common for the air conditioning pipes to freeze up and stop cooling. The main reason is usually an issue with the AC system. For example, if the refrigerant is insufficient, the pressure in the pipes drops, causing the temperature to get too low, which can easily lead to frost forming on the outside and blocking the vents. Or, if the expansion valve fails and can't regulate the flow of cold air, the pipes can freeze severely. Sometimes, a broken fan that fails to dissipate heat can also worsen the icing. My old car once had this problem during a long summer trip—ice buildup blocked the pipes, preventing cold air from getting through, and the cabin became unbearably hot. Later, a mechanic found that the refrigerant had completely leaked out. After refilling it, the AC worked fine again. I recommend regular AC maintenance and checking the cooling system to avoid waiting until problems arise before fixing them.
Last summer when I was driving back to my hometown, the car's air conditioning suddenly stopped cooling, and I noticed thick ice forming on the pipes. After asking a friend, I learned that it might be due to insufficient refrigerant or a leak, causing the pipes to overcool and freeze. Another possibility was that the air conditioning filter was too dirty or the fan wasn't working, blocking airflow and allowing ice to accumulate. A faulty temperature control switch could also cause this, making the compressor run non-stop. At the time, I cleaned the filter myself, which alleviated the problem, but for a long-term solution, I needed to have a professional check for leaks in the system. To prevent such issues, it's good practice to pay attention to any unusual sounds from the air conditioning before driving and to check the refrigerant levels before hot weather arrives.
