How to Deal with Foggy Windows When Using Air Conditioning in Summer?
4 Answers
Solutions for foggy windows when using air conditioning in summer: 1. Appropriately increase the temperature inside the cabin to reduce the significant difference between indoor and outdoor air temperatures; 2. Use the windshield wipers to clear the fog and direct some warm air towards the windshield to quickly disperse the fog; 3. Apply anti-fog agents to the windows, which absorb moisture on the surface and form a water film to prevent fogging; 4. If it rains frequently and opening windows is not suitable, turn on the external circulation defogging mode, ensuring the air vents are correctly positioned to blow air towards the front windshield and footwell or just the front windshield.
I've been driving for almost twenty years and have encountered the issue of fogging up when using the air conditioning in summer quite a few times. You can simply adjust the air vents to the windshield mode—that's the fan-shaped icon on the dashboard—and turn up the fan speed. The cold air blowing directly onto the glass will clear the fog instantly. On rainy days when humidity is high, remember to turn on the external air circulation to keep the air flowing, as using internal recirculation will only make the fog worse. I always keep a bottle of anti-fog spray in the glove compartment. Spray it on the inside of the windshield when parked and wipe it clean, and you won’t have to worry about fogging for a week or two. Also, remember to change the cabin air filter every three to four months—if it's clogged, the dehumidification effect will be poor, making fogging more likely. Never wipe the windshield with your hand while driving—it’s too dangerous. Back in the day, an old buddy of mine rear-ended someone because he was wiping the glass.
Last week when I took the kids out, this exact thing happened - with the car AC cranked up, the windshield suddenly fogged up completely white. I immediately hit the defrost button, and it cleared up in under half a minute. The key is to remember to turn on the AC switch simultaneously, otherwise just blowing air without cooling won't remove the moisture. If there are elderly or children in the car, avoid pointing the vents directly at them to prevent catching a cold. My wife taught me a clever trick: mix dish soap with water and wipe it thinly on the inside of the glass - this protective layer lasts 2-3 days. Another method is to slightly open diagonal windows (left rear and right front) to create airflow that blows away the fog. Keep the AC temperature around 23-24°C - too big a temperature difference actually causes more fogging.
I recently learned how car defogging works when fixing my car. When it's cold inside and hot outside, moisture condenses on the cooler windshield. Turning on the AC for dehumidification works best - remember to adjust the vents to blow upward onto the glass. For older cars with weak AC, try this trick: drive with windows down for 1-2 minutes after starting to equalize interior/exterior temperatures before closing windows and turning on AC. Or alternate hot/cold air: use hot air for 30 seconds to melt fog, then switch to cold air to prevent recurrence. If side mirrors fog up, pressing the rear defroster button also heats them. Be extra careful with aftermarket tinted windows - poor quality films with weak insulation fog more easily. If problems persist, have your AC system checked as refrigerant leaks can affect defogging performance.
