How to Deal with Fog on the Outside of the Windshield When Using Air Conditioning in Summer?
4 Answers
To address fog on the outside of the windshield when using air conditioning in summer, you can increase the cabin temperature, apply anti-fog spray, or open the windows for air circulation. Here are the details: Increase the cabin temperature: When using the air conditioning in summer, you can slightly raise the cabin temperature to reduce the temperature difference between the inside and outside of the vehicle. This prevents water vapor from condensing, thus avoiding fog on the windshield. If fog has already formed, you can first use the windshield wipers to clear it, then direct a small amount of warm air toward the windshield to disperse the fog. If your car has a sunroof, slightly opening it can also help. Apply anti-fog spray to prevent fogging: Fogging on the windshield when using air conditioning is caused by the temperature difference between the inside and outside of the glass. A simple preventive measure is to spray a small amount of anti-fog solution onto the windshield and wipe it clean. This removes dirt and stains while forming a thin, transparent protective film on the glass, effectively preventing water vapor from condensing and forming fog. Open the windows for air circulation: If the fog is not severe, you can slightly open the side windows to allow air to circulate. This helps balance the temperature inside and outside the car, gradually dispersing the fog. This method achieves a cooling effect without increasing fuel consumption, but it is not suitable for rainy or overcast days.
I just started driving and encountered fogging on the outside when using the AC in summer. This is quite common, mainly due to the large temperature difference between the inside and outside of the car, causing external moisture to condense into water droplets on the cold glass. Speaking from experience, here’s the immediate way to handle it: Don’t point the AC vents directly at the windshield—adjust them to blow toward your legs or body. Then, increase the fan speed, as stronger airflow helps disperse moisture. Try switching to the external circulation mode to introduce drier outside air and reduce humidity. If fog forms quickly, simply use the windshield wipers to immediately clear the obstructive mist. For prevention during regular driving: On high-humidity days, briefly use the heater to warm up the glass before turning on the AC to avoid sudden cooling and condensation. After doing this a few times, your visibility will be restored, ensuring safe driving comes first.
In summer, turning on the AC causes fogging outside due to the rapid cooling of moist external air by the cold glass inside the car, leading to condensation. Here's how I deal with it: Adjust the AC settings to avoid direct airflow onto the glass—it's best to use the windshield defogger button, which automatically optimizes airflow and direction; switch to recirculation mode to reduce the relative humidity inside the car; increase the fan speed to enhance air circulation. When fogging is severe, activate the wipers to remove water droplets and ensure the wipers are in good condition to prevent blurring. Additional tips: Check for dust on the glass when parked, as it can worsen condensation; moderate the AC cooling when humidity is particularly high; always ensure clear visibility to avoid accidents.
Fogging on the outside when the AC is on—I’ve seen it plenty in my decades as a seasoned driver. Prevention is key: avoid directing airflow at the windshield when using AC; briefly preheat with warm air before starting to prevent condensation. Practical fixes are simple: turn the fan to high speed to disperse moisture; switch to fresh air mode (external circulation) to reduce humidity; if all else fails, wipe it clean with a cloth or use the wipers. Safety first—if fogging obstructs your view, pull over and clear it. Build good habits: clean window dust when parked, and reduce AC intensity on humid days.
