What are the reasons for slow and insufficient cooling in car air conditioning?

[IslaRose]

Here are the reasons for slow and insufficient cooling in car air conditioning: 1. Insufficient refrigerant due to low refrigerant levels: The main cause of refrigerant shortage is usually 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 in the evaporator, the amount of heat absorbed will decrease, leading to reduced cooling capacity. 2. Moisture infiltration in the air conditioning refrigeration system causing insufficient cooling: There is a component in the refrigeration system called the dryer (or receiver-drier), whose main function is to absorb moisture from the refrigerant to prevent excessive moisture in the refrigerant, which would reduce cooling capacity.

[DeJosie]

Last time I encountered this issue, I figured there must be something wrong. If the refrigerant is leaking and the pressure is low due to insufficient refrigerant, the cold air will come out slowly. The condenser is clogged with dust and dead insects, reducing heat dissipation and causing the fan to struggle. The aging compressor doesn't engage smoothly, leading to slow startup and affecting cooling speed. The evaporator is dirty or frozen, blocking the air ducts and preventing airflow, making it feel less cool. Also, the cabin air filter needs replacement—thick layers of dust block the airflow, reducing cooling efficiency. Parking under the scorching sun for too long causes the cabin temperature to skyrocket, overloading the AC system and slowing down cooling. Regular maintenance, such as checking refrigerant levels and system seals, is often neglected. I recommend visiting a professional shop for a full diagnosis to avoid minor issues turning into costly repairs. Preventive measures, like parking in the shade on hot days and ventilating the car before turning on the AC, can improve performance.