Why is the car air conditioning not cool in outside circulation mode but cool in inside circulation mode?

[MacAriel]

Detailed explanation and solutions for the issue where the car air conditioning is not cool in outside circulation mode but cool in inside circulation mode are as follows: 1. Insufficient or too little refrigerant: 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, the heat absorbed during evaporation in the evaporator will be reduced, leading to a drop in cooling capacity. Solution: Add refrigerant. 2. Excessive refrigerant: The proportion of refrigerant in the air conditioning system must meet specific requirements. If the proportion is too high, it can affect the heat dissipation, meaning more heat dissipation results in greater cooling capacity; conversely, less heat dissipation leads to reduced cooling capacity. Similarly, adding too much cooling oil during maintenance can also decrease the heat dissipation of the refrigeration system. Solution: Slowly release some refrigerant from the maintenance port on the low-pressure side of the air conditioning system.