Why does the car air conditioner not cool at idle but cools when accelerating?

[JosephineLee]

There are several reasons why a car air conditioner may not cool at idle but cools when accelerating, including a damaged expansion valve, internal wear of the air conditioning compressor, and excessively low idle speed. Below are detailed explanations for each cause: Damaged expansion valve: This prevents the formation of high pressure in the system before the expansion valve, causing the high-pressure refrigerant to fail to reach the required 150Kpa pressure. As a result, the evaporator after the expansion valve cannot cool down, leading to inadequate cooling from the air conditioner. Internal wear of the air conditioning compressor: This results in the pressure between the air conditioning compressor and the expansion valve not reaching the required 150Kpa to 200Kpa, preventing the refrigerant in the system from circulating normally and causing the air conditioner to not cool properly. Excessively low idle speed: The car's onboard computer determines that turning on the air conditioner at this time could cause the engine to stall.