What air setting to use when there is fog on the front windshield?

[DakotaMarie]

Both warm and cold air can be used to defog the front windshield. If the weather is cold, it is recommended to use warm air for defogging. The method is: first turn on the air conditioning, adjust the temperature to the warm air setting, and at the same time set the air conditioning switch to the defogging mode. The hot air produced by the air conditioning will dry the fog inside the car. Most modern car air conditioning systems come with a dehumidification function, which can be activated by switching to the cold air dehumidification mode. This will quickly dissipate the fog on the windows, and the effect is more lasting and faster. The principle of warm air defogging is similar to that of cold air defogging—one cools the interior while the other warms the glass. However, when warm air defogging is first turned on, the fogging may temporarily worsen, but it will improve shortly. If conditions permit, warm air defogging can be performed while the car is parked.

[VonBarrett]

I've been driving for half my life, and whenever there's fog on the windshield, I instinctively turn on the heater. This isn't just hot air—once during a winter rain, my windshield suddenly fogged up, startling me so much I nearly hit a tree. Later, I learned to set the air conditioning to the windshield defrost mode, indicated by a button with a window-like icon, and switch to external air circulation to let warm air in from outside. Why not use cold air? Because cold air only makes the glass colder, increasing condensation; warm air, on the other hand, heats the glass surface, speeding up water evaporation. It's also important to turn off the AC compressor unless it's extremely hot, as the compressor dehumidifies but cold air doesn't. Occasionally, cracking the window open for a few minutes to ventilate helps too—just avoid wiping with a cloth, as it smears and worsens visibility. Fog forms quickly, and slow removal is dangerous. Safe driving is paramount, and developing this habit could save your life.