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