Should You Use Internal or External Air Circulation When Defogging Car Windows?
1 Answers
When you press the defogging button, the car's air conditioning system automatically switches to external air circulation because only external circulation can effectively remove condensation. External circulation means that when the heater is turned on, the air blown by the fan comes from outside the car, making the air inside and outside the car the same. Internal circulation, on the other hand, recirculates air from inside the car, creating a completely closed system where the inside and outside air do not mix. It's like having a fan blowing air inside the car. In northern regions during winter, the car's interior temperature is very low in the morning. Turning on internal circulation can help the temperature rise faster. Once the temperature increases, you can switch to external circulation to bring in fresh air. In extremely cold areas like Northeast China, if the temperature hasn't risen, frost or snow can quickly form on the windows, making it difficult to wipe off. Experienced drivers often use an old bank card or similar item to scrape it off cleanly. Some cars don't have an external circulation button—only an internal circulation button. When the internal circulation light is on, it's in internal circulation mode; when the light is off, it's in external circulation mode. Defogging method: During rainy or snowy weather, you don’t need to rely on cold air or internal circulation to defog. Simply prepare a defogging solution in advance and spray it on the windshield.
