What is the Correct Method for Car Defogging?

[IsabelFitz]

Spray a small amount of defogging agent on the inner surface of the car window to remove dirt and stains from the glass. Use the air conditioning's cooling and dehumidifying function to reduce air humidity and eliminate fog. In summer, the humidity of exhaled air is high, causing the windshield to fog up quickly. Use the method of lowering the temperature to remove fog. This can promptly prevent excessive fogging on the windshield, but the temperature of the rear and side windows rises more slowly.

[MaverickAnn]

I've been driving for over ten years and often encounter fogging issues. Usually, I start the engine first, then quickly turn the fan to the highest setting, using the A/C mode for dehumidification, and direct the air vents straight at the windshield. If it's cold, I use the heat mode, but I wait until the engine warms up before switching for better results. At the same time, I turn on the external circulation to expel moisture inside the car and reduce fogging. If necessary, I slightly open the window for ventilation, which clears it up in seconds. I also like to keep the windows clean by regularly wiping the inside with a dedicated glass cleaner to prevent dirt from causing fog buildup. Remember, avoid manually wiping the window while driving for safety; stay focused on control. This method is reliable and prevents secondary fogging.

[DeKhloe]

As a young person, I prefer efficient methods: right after starting the car, I turn on the fan at high speed, press the A/C button for strong dehumidification, and direct the vents toward the windshield. If it's cold in winter, I wait until the engine warms up before switching to hot air. I also crack a window or use the external air circulation for quick ventilation. Once during rainy foggy conditions, this approach cleared the fog instantly and saved time. Regularly cleaning the interior glass helps too—I wipe it with household vinegar water to prevent fogging. Simple actions ensure clear visibility.

[KathrynAnn]

I found that fogging is mainly caused by temperature differences and humidity. The operation is quite simple: with the engine running, turn on the fan with the A/C mode to dehumidify and direct the airflow toward the windshield. Controlling the cabin humidity is key—activating the external air circulation or briefly opening the windows can quickly balance the environment. From a technical perspective, the air conditioning system absorbs moisture to prevent condensation. Consistently following these steps ensures safety and efficiency.