Why does the air conditioning not cool when idling but works normally when driving?

[McHarrison]

Here are the reasons why the air conditioning does not cool when idling but works normally when driving: 1. Expansion valve damage: This prevents the formation of high pressure in the system before the expansion valve, causing the high-pressure refrigerant to fail to reach 150Kpa. As a result, the evaporator after the expansion valve cannot cool down, leading to ineffective air conditioning. 2. Internal wear of the air conditioning compressor: This results in the pressure between the air conditioning compressor and the expansion valve failing to reach 150Kpa~200Kpa, preventing the refrigerant in the system from circulating normally and causing the air conditioning to not cool. The idle speed can be adjusted by modifying the throttle size, among other methods. Generally, the optimal idle speed is the lowest speed at which the engine does not vibrate.