How to Deal with Foggy Windows When Using the Heater in Winter?
2 Answers
When using the heater in winter and the windows become foggy, you can turn on the external air circulation to reduce the fogging. Cars also have a defogging function for the windshield. Initially, the fog on the glass may worsen after activating the defogger, but it will lessen after a while. Fogging occurs due to the significant temperature difference between the inside and outside of the car. To prevent fogging, it's essential to reduce this temperature difference. The breathing of passengers inside the car can also cause the windows to fog up, hence the need to turn on the external air circulation. In winter, after the engine reaches its normal operating temperature, you can set the air conditioning to the highest temperature and turn the fan to its maximum setting for quick defogging. If it's not too cold outside, you can also slightly lower the windows while driving to quickly clear the fog. When using the air conditioning in winter, there's no need to press the AC button, as AC is the cooling function of the car's air conditioning system.
As a new driver, I deeply understand the frustration of windshield fogging up when using the heater in winter. The reason is simple: the temperature difference between the inside and outside of the car causes the moisture from our breath to condense into fog on the cold glass. The key to solving this is dehumidification. I always turn on the air conditioning in cooling mode—it removes moisture from the air, and the fog clears in minutes. Alternatively, pressing the defog button automatically adjusts the airflow. For prevention, wiping the windows when parked and applying anti-fog spray can keep them clear for about a week. Remember not to use recirculation mode for too long—cracking the windows for ventilation also helps. Safety-wise, fogged-up windows reduce visibility and increase accident risks. I’ve found that slowing down, activating the defogger, and then accelerating gives me much more peace of mind. These small habits add up to a much safer driving experience.
