Is it better to use the internal or external air circulation on rainy days?

[StKingston]

On rainy days, the air is humid, and the front windshield is prone to fogging, which can obstruct the driver's view. In such cases, it is best to use the external air circulation and adjust the airflow direction towards the windshield. Here is a brief introduction to internal and external air circulation: 1. Generally, with the windows closed, internal circulation means the air inside the car is recirculated by the fan. Since the passage for outside air is closed, no external air enters, making the air inside rather stuffy; 2. External circulation means that while the air inside the car is being circulated, the system opens the passage for outside air to enter, allowing fresh air from outside to come in, making the air inside more fresh.

[StPatrick]

When driving in rainy weather, I always prefer to use the air recirculation mode because there's a lot of rain and high humidity outside. If I turn on the fresh air mode, the windows tend to fog up, making it hard to see the road conditions, which is quite dangerous. I drive an ordinary car, and every time I start it, I press the AUTO button first to let the air conditioning adjust itself. But when the rain gets heavier, I manually switch to recirculation mode to keep the air dry, which is much more convenient. However, if I keep it on for too long, the air inside the car can get stuffy and stale, especially when there are many passengers. Poor air circulation can easily lead to fatigue, so I switch to fresh air mode every ten minutes or so to ventilate the cabin. This helps prevent fogging while maintaining good air quality. The defrost button in the car is also very useful—pressing it quickly clears the fog. Combined with a moderate air conditioning temperature, it ensures a comfortable ride. Remember to clean the air filter regularly, as accumulated dust can reduce its effectiveness. Safety comes first, so balancing the use of both modes is best.

[OAlexandra]

As a veteran driver with twenty years of experience, I highly recommend using the recirculation mode during rainy days. When rainwater falls on the car, the outside air becomes damp and cold. Turning on the fresh air mode allows moisture to enter, causing the windows to fog up and visibility to blur, which can easily lead to accidents—I’ve learned this from personal experience. The recirculation mode effectively isolates humidity, making the air conditioning more energy-efficient and fuel-saving when operating automatically. However, you shouldn’t keep it on all the time, as accumulated carbon dioxide inside the car can cause dizziness. Switch to fresh air mode for a few seconds when parked or in light traffic to let in fresh air. Develop good habits by combining it with the dehumidification function, and regularly check the air conditioning system’s filter to ensure safe and comfortable driving in the rain, protecting both yourself and your car.

[OAutumn]

As a mom driving with kids, I prefer using the recirculation mode on rainy days. The outside humidity is high, and using the fresh air mode can easily cause the windows to fog up, making it dangerous to see the rearview mirror, especially on the way to school. Recirculation keeps the car dry and warm, so the kids don't complain about the cold. However, I worry about poor air circulation affecting their breathing and health, so I first use recirculation to prevent fogging for a few minutes, then briefly switch to fresh air mode for ventilation. I turn on the air conditioning to mix cool and warm air, keeping the temperature not too low to avoid discomfort. Regularly changing the cabin air filter to eliminate odors is essential, ensuring a fresh and comfortable environment for a safe and pleasant drive.