What Causes Slow Cooling in Car Air Conditioning?
2 Answers
Slow cooling in car air conditioning may be caused by insufficient refrigerant due to low levels. The detailed reasons are as follows: Insufficient refrigerant due to low levels: The primary cause of insufficient refrigerant is typically minor leaks in the system. If the refrigerant level in the air conditioning system is low, the amount of refrigerant sprayed into the evaporator from the expansion valve will also decrease. As a result, the refrigerant absorbs less heat during evaporation in the evaporator, leading to reduced cooling capacity. Moisture infiltration in the air conditioning refrigeration system: 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 from reducing cooling efficiency. However, when the desiccant in the dryer becomes saturated, it can no longer filter out moisture. As the refrigerant passes through the expansion valve's throttle orifice, the pressure and temperature drop, causing the moisture in the refrigerant to freeze in the small orifice. This can obstruct refrigerant flow, increase resistance, or even block it completely. Reduced heat dissipation capacity of the condenser: Due to varying working environments, the condenser located in front of the car engine may become covered with oil, dirt, or debris, reducing its heat dissipation capacity. Additionally, issues with the cooling fan, such as a loose drive belt, reduced fan speed, or high-speed fan problems, can also impair the condenser's heat dissipation. The solution is to clean the condenser surface with a soft brush and promptly address any fan malfunctions.
Last time my car's A/C was cooling slowly, and it took a while to figure out the cause. The main issue was poor heat dissipation from the condenser—cottonwood fluff and dust had clogged the fins, and the refrigerant pressure was also abnormal. The mechanic said high low-side pressure might indicate compressor piston leakage, while low low-side pressure could mean an expansion valve blockage. Refrigerant charge must be precise; too much or too little affects cooling speed. During inspection, the A/C high-pressure line was abnormally hot to the touch, and the blower sounded muffled at full speed, both indicating blockages in the system. After cleaning the condenser and adjusting refrigerant pressure, it now cools quickly and effectively. Refrigerant leaks at pipe connections need thorough inspection—fluorescent dye testing is the most reliable method.
