Should You Use Internal or External Air Circulation When Driving in Winter Rain?

[McJesse]

It is best to use external air circulation when driving in winter rain. Reasons for using external circulation: Using external circulation can expel the steam exhaled by passengers out of the car, preventing cold air from condensing on the windows. If internal circulation is used, it may cause fog to form on the windows, affecting the driver's visibility. How to use external circulation: External circulation allows you to breathe fresh air from outside the car. When driving at high speeds for extended periods, the air inside the car can become stale, making you feel drowsy and less focused. In such cases, you should turn on the external circulation to let outside air in. If the warm air in winter feels too hot, you can turn off the fan and open the external circulation to maintain the interior temperature while enjoying fresh air, which will make you feel more comfortable.

[LaGemma]

As a seasoned driver with years of experience, I prioritize safe driving above all. During winter rain, I strongly recommend using the external air circulation mode. When it's rainy outside with high humidity, keeping the windows shut tight and using only internal recirculation causes moisture to accumulate on the windshield. The moment you open a window, fog forms instantly, severely impairing visibility and increasing accident risks. I recall one rainy night when I opted for internal circulation for warmth, only to end up with a fogged-up windshield that nearly caused a collision. Using external circulation brings in fresh, dry air that effectively dehumidifies and prevents fogging. If the cabin feels too cool, simply increase the AC temperature to compensate. Additionally, remember to activate the defogger mode, directing airflow toward the windshield for clear visibility while maintaining warmth. Wet roads demand extra caution—never compromise safety to save a bit on heating. If concerned, briefly switch to internal recirculation occasionally, but keeping external circulation on most of the time is the safer, more reliable choice.

[LePatrick]

I place great emphasis on health and comfort, always considering air quality issues while driving. In winter rain, it's best to use the external air circulation because although the internal circulation keeps you warm, it traps moisture inside the car, leading to more severe window fogging; worse still, prolonged lack of fresh air causes carbon dioxide and bacteria to accumulate in the cabin, making people feel dizzy and fatigued. I've personally experienced driving with internal circulation for several hours in the rain, resulting in family members feeling nauseous. Using external air circulation introduces outside air—though slightly cooler—it balances humidity and improves oxygen levels, making driving more refreshing. If the rain is heavy and the air is unclean, use internal circulation for an hour before switching back to external circulation for ventilation. Combined with setting a comfortable temperature on the AC, this prevents fogging while maintaining health. Don't overlook this detail—driving in the rain is already challenging, and good air quality significantly boosts mood and safety.

[Finn]

As an economical and practical car owner, I prioritize fuel efficiency and effectiveness. During winter rain drives, using the external air circulation is more cost-effective. Although internal circulation heats up faster and saves a bit of fuel, the high humidity on rainy days makes it prone to fogging up with internal circulation. Once fogging occurs, you have to turn up the fan to defog, which consumes more electricity and fuel. Through practice, I've found that turning on external circulation before fogging occurs, introducing dry cold air to prevent fogging, works best. If the rain is light and humidity is low, occasionally switching to internal circulation for warmth is acceptable. It's like finding a balance—don't sacrifice clear visibility for fuel savings. Normally, setting the temperature around 22°C with external circulation as the primary mode is ideal. Automatic air conditioning is even better; just press AUTO and let it intelligently switch modes. This way, fuel consumption stays manageable without causing mental fatigue.

[GageLynn]

As a new driver who just got my license, I encountered rainy winter days shortly after starting to drive. At first, I kept making the mistake of using the recirculation mode, which instantly fogged up the windows and made it impossible to see anything. I had to pull over in a panic. Later, I learned that on rainy days with high humidity, using the fresh air mode is key—letting outside air flow in helps dehumidify and prevents fogging. Using recirculation just traps moisture inside and causes problems. Now, I immediately switch to fresh air mode when getting in the car. If it's cold, I turn up the temperature a bit and press the defrost button to blow air on the windshield—problem solved. Automatic AC is worry-free; just press the AUTO function and it handles the air circulation automatically, letting me focus on driving even in the rain. Remember, don't overthink the temperature settings—clear visibility is what matters most.

[BrooklynFitz]

I absolutely love delving into car knowledge and have experimented with various air conditioning modes. In winter rainy conditions, I prioritize using the external circulation mode: it allows relatively dry air from outside to enter the car and dilute the humidity inside, preventing window fogging. During heavy rain or foggy weather, I briefly switch to internal circulation for warmth, but never for more than half an hour to avoid faster fogging. Setting the fan speed to a moderate level and activating the defogging function automatically switches to external circulation to blow air onto the windows, ensuring both comfort and safety. I often remind myself to frequently check for fogging changes during rain and flexibly adjust the circulation mode to maintain driving comfort.