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

[MacKevin]

For short winter trips, using internal air circulation is sufficient as it provides faster heating efficiency. For long-distance driving, consider starting with internal circulation and periodically switching to external circulation. If the outside air quality is poor, use external circulation with caution. Internal air circulation in car air conditioning exchanges air within the vehicle's interior, while external circulation draws outside air into the cabin. When only internal circulation is used during driving, the carbon dioxide exhaled by passengers cannot be expelled, which may eventually cause symptoms like chest tightness and dizziness. Additionally, when interior temperature and humidity are too high, it's easy for fog to form on the windshield. When starting your car in winter, it's best to first use internal circulation to reach a comfortable interior temperature. After entering the vehicle, drivers should also appropriately activate external circulation to ensure proper air flow inside the cabin.