Should You Use Internal or External Air Circulation When Turning on the Heater in Winter?

2 Answers
GiselleFitz
07/24/25 9:10am
Whether to use internal or external air circulation when turning on the heater in winter depends on the situation: use internal circulation for short trips and external circulation for long trips. Internal and external air circulation in cars refer to: 1. Internal circulation means the air conditioning system is closed to outside air and can only circulate the air inside the car; 2. External circulation means the air conditioning system is open to outside air and draws in air from outside the car for circulation. The functions of a car's air conditioning system are: 1. To cool, heat, ventilate, and purify the air inside the car; 2. To provide a comfortable environment for passengers, reduce driver fatigue, and improve driving safety.
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DelJoy
08/11/25 4:36am
As a seasoned driver with years of experience, I've encountered the issue of using car heaters in winter countless times. I believe the key lies in balancing rapid heating and anti-fogging needs. When you first get into a freezing cold car, decisively turn on the recirculation mode - this makes the warm air circulate inside the vehicle, heating up incredibly fast. You'll feel warm within seconds. However, keeping recirculation on continuously leads to poor air circulation, and the moisture from breathing will cause windows to fog up, seriously compromising visibility and safety. Therefore, after 5-10 minutes, promptly switch to fresh air mode to let outside air in. This both defogs windows and prevents stuffy air, especially effective when carrying passengers or on long trips. Remember to slightly reduce fan speed before switching modes to avoid a sudden blast of cold air. Once this becomes habit, winter driving becomes much more comfortable and safer. I often recommend this method to novice drivers too.
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