Why Does the Low-Pressure Pipe of a Car's Air Conditioner Freeze?

[LeMiles]

The reason for the low-pressure pipe of a car's air conditioner freezing is due to a malfunctioning expansion valve or a failed evaporator temperature sensor. Below are the related explanations for the faults: 1. Malfunctioning Expansion Valve: The low-pressure pipe of a car's air conditioner freezing is most likely caused by a malfunctioning expansion valve, which fails to sense the real-time temperature of the low-pressure pipe. If the temperature is too low, the low-pressure pipe will inevitably freeze (the expansion valve's opening cannot be adjusted lower). This issue is generally irreparable, and a new expansion valve needs to be replaced. 2. Failed Evaporator Temperature Sensor: It may be due to a failed evaporator temperature sensor. This component is designed to detect the surface temperature of the evaporator and transmit the data to the automatic air conditioning control unit. When the temperature drops below 2°C, the air conditioner will stop operating to prevent frost or ice formation. If the evaporator temperature sensor fails, it naturally cannot detect the corresponding temperature data, leading to the low-pressure pipe freezing. In this case, a new sensor needs to be replaced.