Which Button to Press for Foggy Windows on Rainy Days?
3 Answers
Press the defogging button, turn on the air conditioning cooling (A/C) switch, set the temperature to the lowest, and activate the external circulation to remove fog. 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 glass and achieving defogging. The method for using warm air to defog is the same as using cold air, but it's important to note that warm air should not be used for defogging on rainy days, as it can initially worsen the fog. Always use external circulation when defogging car windows. The reason for foggy car windows: There is a certain temperature difference between the inside and outside of the car. If the temperatures inside and outside the car are different, the surface with the lower temperature will have a lower saturated vapor pressure than the surrounding environment, causing water vapor to gather on the glass surface and form tiny water droplets, resulting in fog.
Foggy windows on rainy days can indeed be annoying. When dealing with it, I simply press the windshield defogger button, which usually has a curved line pattern or a window icon, located on the air conditioning panel. Pressing it automatically turns on the AC and blows dry air to dehumidify. The effect is quick, clearing the fog in just a few seconds—don’t forget to increase the fan speed to ensure even airflow coverage on the glass. Why do windows fog up easily in the rain? It’s because the humidity inside the car mixes with the external rain and fog due to temperature differences. Safety first—promptly pressing the defogger button prevents blurred vision and potential accidents. For the rear window fogging up, press another button with a heating icon. Keeping the windows clean regularly also helps by reducing fog buildup.
When fogging occurs, I usually press the defogging button—that small button with a glass and wavy lines in the air conditioning control panel. The operation is simple: first turn on the AC system, ensure it’s set to external circulation mode to enhance ventilation, then press the defogging button. Most cars default to blowing air onto the front windshield, and the fan speed can be manually increased to accelerate dehumidification. The principle is to use dry, warm air to eliminate internal condensation. Fogging is especially frequent on rainy days, mainly due to high humidity and significant temperature differences—early intervention reduces risks. If the button doesn’t work, check the interior/exterior temperature sensors or the condition of the AC filter. Never wipe fog manually while driving, as it can distract you and cause accidents. Regular interior cleaning helps slow moisture buildup.
