How to Deal with Fogging on the Outside of the Windshield When Using Air Conditioning
3 Answers
Generally, the windshield defrosting function can be used to treat the windshield based on the driving environment. If the vehicle is equipped with automatic air conditioning and allows selection of air outlet positions, it is recommended to choose the windshield and center air outlet positions, and turn on the rear windshield heating function. If it is not possible to select two directions for air output simultaneously, turn on the windshield defrosting function and rear windshield heating function, especially if the side windows are fogged up. You can also slightly open the windows to quickly remove the fog. After closing the windows, once the interior temperature rises, no fog will form.
I used to frequently encounter the issue of fogging on the outside of the windshield when turning on the AC, which was quite annoying as it obstructed visibility. The key reason is that the cold air inside the car lowers the temperature of the outer surface of the glass, causing moisture in the humid outside air to condense into fog. Dealing with it isn’t difficult—first, try adjusting the AC airflow to the windshield mode and increase the fan speed for better defogging. At the same time, switch to external air circulation to reduce interior humidity and minimize temperature differences. If fogging persists, after parking, wipe the glass with a clean towel or spray some glass cleaner to keep the surface clean and fog-free. Remember to check if the cabin air filter is clean before driving, as a clogged filter can reduce effectiveness. Developing good habits, like avoiding blasting the AC at full power right after entering the car on rainy or hot days, can effectively prevent such issues. Don’t underestimate it—improper handling can compromise driving safety. These methods have helped me avoid many close calls—they’re truly practical and simple.
As someone who frequently works on cars, the core issue of fogging on the outside of the windshield is condensation: the AC cools the glass, causing external moisture to condense into fog. When dealing with it, don’t rush to wipe it by hand—first activate the car’s defogging mode, direct the airflow toward the windshield, and set the fan speed to medium-high for quick dehumidification. Also, check the AC system, such as whether the filter is clean, as a dirty one can trap moisture and worsen the problem. Lower the AC temperature slightly but avoid extreme cold to prevent excessive temperature differences. External factors matter too—cleaning the glass with a dedicated anti-fog solution provides long-lasting protection, especially in humid weather. Regular vehicle maintenance, like clearing drainage holes and ensuring good cabin ventilation, reduces moisture buildup. These steps not only address fogging but also enhance overall driving comfort, preventing last-minute panic that could lead to accidents.
