What to Do When the Car Windows Fog Up After Leaving an Underground Garage?

[LaJasmine]

Press the defogging button, which has an icon of three upward-curved arrows inside a square, located at the lower right corner of the center console. Turn on the air conditioning (A/C) to the coldest setting and activate the external air circulation to defog the windows. Both cold and warm air can be used to defog car windows, but warm air is slower than cold air. The most effective method is to use cold air, which blows dry, cold air directly onto the glass, preventing water vapor from condensing on the surface and achieving defogging. The warm air method works similarly, but note that it should not be used on rainy days as it may initially worsen the fogging. Always use external air circulation when defogging car windows. The reason car windows fog up: There is a temperature difference between the inside and outside of the car. If the temperatures differ, the side with the lower temperature will have a lower saturated vapor pressure, causing water vapor to condense on the glass surface in tiny droplets, forming fog. Methods to defog car windows: Air Conditioning (Cooling Mode): Use the air conditioning's dehumidification function to reduce air humidity and remove fog. In summer, especially when multiple people enter the car without turning on the AC, the exhaled humid air can quickly fog up the windshield. Turning on the AC to blow cold air onto the windshield can help dehumidify and clear the fog quickly. If humidity is too high and the AC alone is ineffective, slightly opening the windows can rapidly reduce cabin humidity. Combining both methods yields faster results. Air Conditioning (Heating Mode): Use warm air to reduce the temperature difference and prevent fogging. In winter, blowing warm air onto the windshield raises its temperature, minimizing the temperature difference between the inside and outside surfaces and preventing heavy fogging. However, the rear and side windows warm up more slowly, requiring more time to fully defog. Whether using automatic or manual AC, turning it on aids dehumidification. Avoid setting the temperature to the coldest to prevent external windshield fogging over time. Applying Anti-Fog Products: Spray a small amount of defogging agent onto the car windows and wipe it clean to remove dirt and stains. This leaves a transparent protective film that effectively prevents water vapor from condensing into fog, especially useful in cold winters. Alternatives like dish soap, soapy water, glycerin, alcohol, or saline can also be applied. After drying, wipe off excess residue with a chamois or soft cloth to keep windows fog-free for several days.