What Causes High-Pressure Pipe Freezing in Passat's Air Conditioning System?

[VanAlina]

High-pressure pipe freezing in the air conditioning system is caused by either expansion valve failure or temperature sensor malfunction. Reasons for car air conditioning system freezing: 1. The expansion valve's adjustment range is too small, resulting in excessively low low-pressure; 2. Insufficient refrigerant in the system leads to low evaporation pressure; 3. Clogged internal circulation filter; 4. Faulty temperature control (or temperature sensor) causing continuous compressor operation; 5. Malfunction of variable displacement compressor's energy control valve (pressure regulating valve), keeping the compressor at full capacity and causing excessively low pressure that leads to evaporator frosting. Causes of evaporator freezing in car air conditioning: Possible reasons for evaporator freezing include: - Compressor's self-regulation function failure; - Incorrect refrigerant charge amount; - Moisture presence in the system; - Blockage in system pipelines. For poor evaporator ventilation, primarily inspect the air conditioning thermostat (temperature control switch) for faults. Normally, car air conditioning evaporators shouldn't freeze. Evaporator freezing indicates air conditioning system issues.