What circulation mode should be used on rainy days?

[Presley]

On rainy days, the external circulation mode should be activated. Introduction to the vehicle's circulation system: All car air conditioning systems have both internal and external circulation modes, but many drivers don't use the internal circulation correctly. When driving long distances or on highways where opening windows for ventilation isn't convenient, it's recommended to use external circulation. For driving in congested urban traffic, internal circulation is advised. Additional notes on the circulation system: Vehicle air conditioning systems are equipped with cabin air filters that require regular replacement. Most vehicles need these filters changed every 10,000 kilometers. The cabin air filter purifies incoming air - failing to replace it regularly will compromise the air conditioning's effectiveness and potentially affect passengers' health.