How to Turn on the Car Heater for Defogging?
3 Answers
To defog using the car heater, turn on the air conditioning's warm air and wait for it to dry the fog on the windshield. It's important to note that you should not use hot air for defogging while driving. Initially, turning on the hot air may not only fail to remove the fog but could also worsen the fogging on the windshield, significantly increasing safety hazards. Air conditioning can adjust temperature: This is the primary function of car air conditioning. In summer, the cooling system produces cold air to lower the temperature inside the cabin. In winter, except for large commercial vehicles that use independent combustion heaters for warmth, other vehicles mainly utilize the car's residual heat for heating. Air conditioning can adjust humidity: Humidity greatly affects the comfort of passengers inside the car. The humidity inside the cabin should generally be maintained between 30% to 70%. Standard car air conditioning systems do not have the capability to adjust cabin humidity. This can only be achieved by using ventilation systems or the advanced integrated heating and cooling systems found in luxury vehicles. Air conditioning can adjust airflow: The speed and direction of airflow significantly impact passenger comfort. If the air is blowing directly, the speed should be limited to a certain range when the temperature is appropriate. The airflow speed can be adjusted based on passengers' living environment, age, health condition, and temperature preferences.
I've been driving for nearly twenty years, and using warm air to defog the windshield is my specialty. You need to start the engine first, let the car warm up, then turn on the fan to the warm air setting, adjust the temperature control knob to the hot side, preferably around 25 degrees. Next, direct the airflow toward the windshield—that's the button on the AC panel with the glass symbol. Remember to press the A/C button; it helps dehumidify the air, making the fog clear much faster. I often do this in winter or rainy weather—it clears up in just a minute or two, but wait until the fog is gone before driving off for safety. Another tip: crack the windows slightly to let out some moisture before defogging for better results, and don’t forget to regularly check the cabin air filter to avoid clogging and reduced performance.
When I first started driving, I knew nothing about defogging and would randomly press buttons when the fog got heavy. Now I understand the correct steps. After starting the car, immediately turn on the air conditioning system, set the fan speed to medium-high, select warm air temperature (roughly turn it to the red zone). Adjust the air direction control to point at the windshield—find and press the button with the windshield icon. Turning on the A/C can quickly remove moisture; if there isn’t much fog, lower the fan speed. After these steps, wait a few dozen seconds for the windshield to clear, but safety first—don’t rush to drive. This method is most useful on rainy days or in the morning—easy to master and practical.
