Do You Need to Turn on AC for Defogging in Winter?
2 Answers
In winter, you don't need to press the AC button for defogging. You can use either cold air or warm air to remove fog from the windshield. Compared to warm air, cold air is less effective, so warm air is generally preferred for defogging, and the AC does not need to be turned on when using warm air. Here’s more about the AC: 1. A/C stands for Air Condition, which refers to air control or air conditioning. In cars, it is understood as the air conditioning cooling switch and also represents the air conditioning compressor. The AC button needs to be pressed when turning on the air conditioning in summer, but it is not necessary in winter. When the air conditioning compressor is activated, the engine's load increases, leading to higher fuel consumption. 2. During winter driving, once the engine's coolant temperature rises, activating the heating function will gradually increase the temperature inside the car. Although the absolute humidity in the space remains unchanged, the high temperature causes water molecules to move vigorously, preventing them from condensing into fog, thus achieving the defogging effect. 3. Therefore, when using cold air for defogging, the AC needs to be turned on, but it is not required when using warm air. 4. In winter, when the heating is on, the heat produced by the air conditioning mainly comes from the coolant, which is used to cool the engine. The engine typically maintains a temperature of around 90 degrees during normal operation, making warm air more effective for defogging in winter.
I've encountered fogging issues countless times while driving in winter. At first, I thought using AC would make me feel uncomfortably cold, but actually it's a dehumidification expert that can quickly remove moisture from the car and clear fog faster. When combined with warm air blowing on the windshield, the cabin temperature doesn't drop significantly. Instead, visibility improves rapidly, making driving safer. I've also noticed that wet shoes during rainy days can worsen fogging, but turning on the AC can help alleviate it. Don't forget to regularly check your AC system to prevent aging from affecting its performance.
