Why does the car make a hissing sound like air leakage when the air conditioner is turned on?

[StGeorge]

Car makes a hissing sound like air leakage when the air conditioner is turned on is the refrigerant airflow noise caused by the throttling of the expansion valve in front of the evaporator in the car air conditioning system. As long as the operating condition is slightly changed, such as adjusting the fan speed, the sound will disappear. The car evaporator is a component in the air conditioning system. Its function is to allow low-temperature condensed gas to pass through the evaporator, exchange heat with the outside air, absorb heat through liquefaction, and achieve the cooling effect. Car air conditioning refers to the air conditioning device installed in the car, which can cool, heat, ventilate and purify the air in the compartment, providing a comfortable riding environment for passengers, reducing the driver's fatigue and improving driving safety.