Should You Use Internal or External Air Circulation for Dehumidifying the Car Interior?
5 Answers
Use external air circulation for dehumidifying the car interior. Below are situations when external circulation should be used: 1. After purchasing a new car: After buying a new car, you should open the external circulation as much as possible to maintain air flow between the inside and outside of the car, allowing harmful gases inside the car to evaporate and dissipate quickly. This is similar to opening windows for ventilation when moving into a new house. 2. Smoking in the car: If you like to smoke in the car, whether the vehicle is stationary or moving, you must turn on the external circulation to ensure smoke is quickly expelled from the car. This not only protects your health but also reduces the harm of secondhand smoke to other passengers. 3. Long-distance high-speed driving: During long high-speed drives, keeping the internal circulation on can easily lead to insufficient oxygen inside the car, causing driver fatigue and potential traffic accidents. In this case, switch to external circulation to replenish fresh air inside the car.
I've been driving for decades and have encountered the issue of car dehumidification countless times, mainly during the rainy season when foggy windows are annoying. The key to dehumidification is turning on the A/C because the air conditioning can condense and expel moisture. I usually use the external air circulation, especially after rain when it's sunny or the air is dry, letting outside air in to remove the humidity inside the car faster. However, if it's foggy or the humidity is extremely high, like during the southern rainy season, turning on the internal air circulation with the A/C for a few minutes can quickly remove the fog, ensuring safety and peace of mind. I remember that long trip when I used external air circulation with cool air, and once the car was dry, I could focus on the road. In short, don't forget to regularly check the air conditioning filter to avoid blockages.
As parents of two kids, car dehumidification is my top priority—don't let the rear window fog up and affect safe driving. It's recommended to first turn on the A/C for core dehumidification, and setting the fan to a higher speed works better. Using the external air circulation mode during dehumidification is usually more effective, as it introduces fresh air and prevents the kids from feeling stuffy; if it's raining heavily outside and very humid, temporarily switch to internal circulation, and the A/C will clear the moisture in just two minutes. Remember to clean the air vents regularly to prevent mold buildup after prolonged A/C use. Good ventilation habits can extend the equipment's lifespan.
From the perspective of the vehicle's infotainment system, dehumidification relies on the A/C to condense moisture. Turning on the cold air is fundamental, and selecting the external circulation mode makes it easier to reduce humidity, allowing dry outside air to flow in and accelerate the dehumidification process. If there are multiple internal moisture sources, such as residual wet clothing, briefly using the internal circulation cold air can provide more concentrated treatment. The ventilation system is designed to prioritize external airflow to prevent moisture buildup. Maintaining the air conditioning system to ensure normal functionality is crucial.
Driving to and from work every day, dehumidifying is a routine task. I'm used to pressing the A/C button to dehumidify with one click. Most of the time, using the external air circulation feels comfortable as it maintains airflow to disperse moisture—especially effective in the morning when the windshield frosts up. During rush hour traffic or in heavily polluted areas, switching to internal air circulation helps quickly remove damp fog, which is more practical. Make sure to replace the cabin air filter regularly to maximize airflow and speed up dehumidification. Keep it simple; no need to overcomplicate things.
