Should I Use Hot or Cold Air to Defog the Car?
2 Answers
In winter, when fogging occurs inside the car, warm air should be used to defog. If fogging occurs in summer, cold air should be used. Hot air can also defog, but it may take a longer time. Whether it's summer or winter, opening the car windows can quickly defog the car. Here are some additional tips on defogging: 1. Open windows for convection: Opening windows for convection is a convenient and quick method to defog by lowering the temperature inside the car. However, this method has certain limitations and is not practical in rainy, snowy, or heavily foggy weather. 2. Use the rear windshield and side mirrors for defogging: Currently, many car models are equipped with rear windshield heating features, which can clear fog in about a minute.
I've been driving for so many years and have plenty of experience with defogging. When the weather is cold, I usually blast the cold air first to instantly disperse the fog—visibility clears up immediately, but the car gets unbearably cold after a while. Once the engine warms up, I switch to hot air. Although it gets blurrier for the first few minutes, persisting with it will clear all the fog while keeping the cabin warm and cozy. Remember to press the A/C button when using the AC—it dehumidifies, and that’s the key. Set the airflow toward the windshield. In winter, start with external circulation to ventilate, then switch to internal circulation to retain warmth. In summer, cold air plus A/C is the easiest—no need for hot air at all. In short, use cold air as an emergency fix when you first get in the car, then switch to hot air after driving for a while—that’s the golden rule.
