Should You Use Internal or External Air Circulation in the Car During Winter?

[LeArianna]

Whether to use internal or external air circulation in winter depends on the situation. Here are the relevant details: When to use internal circulation: When the weather is very hot in summer or very cold in winter, drivers usually turn on the internal circulation mode to maintain a comfortable temperature inside the car and reduce the workload of the air conditioning system. When to use external circulation: When the outside air is particularly fresh, or when driving through areas with lush vegetation such as scenic spots or suburbs, you can turn on the external circulation to "vent" the stale air inside the car. Additionally, on rainy days, because the outside temperature is lower, the exhaled air from passengers can condense on the windows, forming a layer of fog. In this case, turning on the external circulation helps balance the internal and external temperatures, causing the fog to gradually dissipate.

[PeytonDella]

Using the air recirculation mode in winter driving is an important topic. As a daily commuter, my habit is to turn on the recirculation mode immediately after starting the car to quickly warm up the cabin, as the interior is too cold at first. Recirculation allows heat to circulate inside the car, improving heating efficiency and saving fuel. However, after about ten minutes when the temperature becomes comfortable, if the windshield fogs up, I switch to fresh air mode (external circulation) for defogging, as introducing dry outside air is most effective for clearing fog. Avoid using only recirculation mode for extended periods, as stale air and CO₂ buildup can cause driver fatigue, especially dangerous during long trips. Additionally, if your car has automatic climate control, pressing the AUTO button lets the system balance recirculation and fresh air modes effortlessly. Remember to switch flexibly between the two for optimal safety and comfort in winter, particularly in cold regions with icy roads.

[DelHarley]

Experienced drivers will tell you that timing is key when using the air recirculation mode in winter. When starting your car in freezing weather, prioritize the recirculation mode to warm up the cabin faster, keeping you from catching a chill. However, once the heating phase is over or after about half an hour of driving—especially when you start feeling warm—it's crucial to switch to fresh air mode. This effectively defogs the windshield, ensuring clear visibility, which is vital on icy or snowy days. The fresh air mode also maintains airflow, preventing odor buildup and keeping the driver alert. In practice, I recommend using recirculation mode initially for quick heating, then switching to fresh air mode once the engine reaches operating temperature. This simple and safe approach prevents misuse over time, ensuring a healthy cabin environment and keeping drowsiness at bay during cold winter drives.

[DiSienna]

For family users, it's important to pay attention to comfort and health when setting the car air conditioning in winter. Every time I start the car, I first turn on the internal circulation to warm up quickly so my child doesn't get cold. But once it's warm, I switch to external circulation to defog and introduce fresh air to prevent fogging and ensure my child's safety. This switching method prevents stuffy air that could cause motion sickness.