Do You Need to Turn on the AC Button in Winter?

[NolanAnn]

You don't need to turn on the AC button in winter. The AC button is the switch for the air conditioning compressor. In summer, when using the air conditioning, you must turn on the AC button to activate the cold air. The warm air, however, simply utilizes the internal heat circulation of the car and does not require the air conditioning compressor to be activated. Therefore, to use the warm air, you only need to adjust the air conditioning controls without turning on the AC switch. The warm air comes from the heat generated by the engine during operation: after the engine's cooling system dissipates heat from the engine, a fan directs this heat into the car to create warm air. When the warm air is not in use, the fan stops, the heating vents close, and the dissipated heat is completely released into the atmosphere. Thus, the car's warm air is a form of waste heat recycling and does not consume additional fuel.

[Gutierrez]

I often deal with foggy windows when driving in winter, and actually pressing the AC button works really well. The AC button isn't just for cooling in summer; once its compressor starts, it can remove moisture from the air, making the windows less prone to fogging. I usually turn on the AC as soon as I get in the car, combined with the external air circulation, and the fog dissipates in seconds, which is faster than just using the heater. However, keeping the AC on for too long can make the car too dry, even causing chapped lips, so I turn it off once the fog is gone and just leave the heater on. If you never use the AC in winter, on rainy or cold days, the windshield can fog up in minutes, which is really dangerous. Also, the compressor can easily get damaged if the AC isn't used for a long time, so I make sure to turn it on occasionally to keep it running.

[McDeclan]

Whether to turn on the AC in winter depends entirely on the humidity inside the car. Based on over twenty years of driving experience, I've found that during rainy days or when there are many passengers exhaling moisture, the AC must be activated to dehumidify. Otherwise, fog can obstruct visibility, making it impossible to see the road clearly. Once the AC compressor is running, the humidity of the air blown out drops significantly, and when combined with warm air, it removes fog extremely quickly. However, some cars may feel slightly sluggish when the AC is on, possibly increasing fuel consumption by a small margin. Therefore, I only turn it on when the fog is heavy, using it for a few minutes until the fog clears and then turning it off. On normally dry and cold days, there's no need to use the AC; circulating warm air is sufficient and saves some fuel. Remember, regular checks of the air conditioning system are crucial, and running the AC occasionally in winter helps maintain the compressor's health.

[SanEmmett]

I drive my kids to school, and the most annoying thing in winter is the foggy windows. My husband taught me to use the AC button for dehumidification, and the effect is really noticeable. When the AC is on, the cold air absorbs moisture, making the car interior dry and the windows clear. Adding a bit of warm air heats things up quickly. But don't keep the AC on all the time, or it will make your mouth and throat uncomfortably dry. I usually turn it on for a while when the fog is severe and switch back to pure warm air mode after the fog is gone. When parking in cold weather, water vapor on the windows can also cause fogging. Turning on the AC with the defog button before setting off clears it up in seconds. If an older car's AC isn't working well, it might need repairs.

[SanElias]

The dehumidification effect of turning on the AC in winter is truly impressive. I've tried it—when the temperature is below freezing, the car interior stays warm and cozy, but exhaled breath immediately condenses on the windows. Turning on the AC at this point, the compressor swiftly removes the moisture, and the windows clear up instantly, boosting driving safety. However, keeping the AC on continuously blows air that's too cold, so you need to raise the temperature setting for comfort. Occasionally turning on the AC is also good for the compressor, preventing it from rusting due to inactivity. This method is especially useful in humid southern regions. But in dry areas, there's no need to use it, as it would just waste fuel.

[DeJason]

Window fogging in winter is a safety hazard, so I always turn on the AC for dehumidification when driving. Even at very low temperatures, the AC combined with the heating system can quickly defog the windows, ensuring clear visibility. However, be aware that running it for too long can dry out the car's interior, causing skin discomfort. I usually turn off the AC once the fog clears and continue using the heating system with external air circulation. If you don't use the AC, relying solely on hot air for defogging is slower and consumes more fuel. Regularly using the AC is beneficial for maintaining the air conditioning system, especially for cars that are not used frequently.