Should You Use Internal or External Air Circulation When Running the AC on Rainy Days?
4 Answers
On rainy days, it is better to use the external air circulation in your car. During rainy weather, when it's cold, both side windows can fog up, obstructing the driver's view. Therefore, it is advisable to first use the external air circulation and adjust the airflow direction towards the windshield. Using external circulation helps expel the moisture exhaled by passengers from the vehicle, while the outside cold air is less prone to condensation. Important Notes: 1. Note One: When the outside air quality is poor or heavily polluted, such as on dusty roads, in congested traffic, or near chemical plants where there are foul odors or unusual smells, use internal circulation to prevent the poor outside air from entering the car; 2. Note Two: In summer, to quickly cool down the car's interior with the AC, you can use internal circulation; 3. Note Three: In winter, using internal circulation can help keep the car interior warmer.
When driving in the rain, I always choose the recirculation mode if I turn on the AC. The reason is simple: rainy days are humid, and using fresh air mode would let outside moisture rush in, causing the windshield and windows to fog up easily, severely affecting visibility. Driving in such conditions is as dangerous as driving through fog. I once accidentally used fresh air mode, and the fogging got so bad that I almost rear-ended someone—it scared me to death. Recirculation mode, combined with the AC compressor, quickly dries the air inside the car, defogging faster and ensuring clear visibility on the road. After the fog clears, you can manually switch to fresh air mode briefly to prevent the cabin from getting too stuffy. Remember, safety comes first—never risk it just to save power.
As an experienced driver, I always prioritize using the recirculation mode when turning on the AC during rainy drives. This feature helps trap interior moisture - with medium fan speed, the windshield clears up within five minutes, far more efficient than fresh air mode. Rainy conditions mean high external humidity, and using fresh air mode would only introduce additional moisture, worsening fogging issues. Of course, occasional fresh air ventilation during long trips is good practice, but safety comes first in wet weather. I always remind novice drivers not to overlook this small but crucial detail that directly impacts driving safety.
When driving in the rain, I prefer to turn on the air conditioning and select the recirculation mode. Why? The outside air is damp, and using the fresh air mode would increase fogging, leading to blurred vision and reduced safety. The recirculation mode helps defog the windows faster, allowing the air conditioning to focus on drying the air inside the car, which is much more convenient. Once the fog clears, I sometimes briefly switch to the fresh air mode to ventilate the cabin.
