What Causes Car Air Conditioning to Frost Up and Not Cool?
2 Answers
Car air conditioning frosting up and not cooling is a phenomenon known as ice blockage in the refrigeration system, primarily caused by moisture in the refrigerant. Below are additional details: 1. Insufficient Refrigerant: Sometimes, insufficient or low levels of refrigerant in the car's air conditioning system can lead to a lack of cooling. The main reason for refrigerant shortage is often minor leaks in the system. If there is insufficient refrigerant in the air conditioning system, the amount of refrigerant sprayed into the evaporator from the expansion valve will also decrease. Consequently, when the refrigerant evaporates inside the evaporator, the amount of heat absorbed will diminish, leading to reduced cooling capacity. 2. Moisture Infiltration: The presence of moisture in the car air conditioning's refrigeration system can cause insufficient cooling or a complete lack of cooling. If moisture infiltration is the cause of the cooling failure, it is necessary to replace the desiccant or dryer in the car's air conditioning system. Additionally, the system should be evacuated and recharged with an appropriate amount of new refrigerant.
I've studied the issue of air conditioning evaporator frosting multiple times, and there are mainly three possible causes. First, overcharging of refrigerant can lead to excessive pressure that causes icing. Second, a malfunctioning evaporator temperature sensor may provide inaccurate readings, causing the compressor to run continuously. Third, a completely clogged cabin air filter or inoperative blower fan can trap cold air in the ducts. Additionally, prolonged use of recirculation mode creates excessive humidity that contributes to this problem - I recommend switching to fresh air mode. My suggestion is to first turn off AC and run the blower at maximum speed for five minutes. If the ice melts and cooling resumes, the issue isn't serious. Otherwise, professional inspection of the expansion valve and system pressure is necessary. Such problems shouldn't be delayed, especially in summer when driving without AC becomes unbearable.
