Do you need to use AC in car air conditioning in winter?

[MacMackenzie]

Car air conditioning does not require the use of AC in winter. The warm air in winter comes from the heat generated by the engine during operation. When the engine's cooling system dissipates heat from the engine, the dissipated heat is blown into the car through a fan, forming warm air. When the warm air is not in use, the fan stops, and the warm air outlet closes, causing the dissipated heat to completely disperse into the atmosphere. When the AC button inside the car is turned on, the entire car air conditioning's evaporator is activated accordingly. When the evaporator is in operation, its temperature is relatively low. As air passes through the evaporator, the water vapor inside is rapidly cooled into water droplets. If the air passes through the evaporator and then is heated by the warm air exchanger, the hot air blown into the car will be drier, making it less likely for the car windows to fog up.

[HenryRose]

When driving in winter, the AC function of the air conditioning doesn't necessarily need to be turned on—it mainly depends on the specific situation. After years of driving, I've found that the heating function alone can warm up the car, while the AC is primarily used for cooling or dehumidifying. If the windshield fogs up, turning on the AC can speed up dehumidification and quickly clear the fog. But if there's no fogging, I turn off the AC to save some fuel. Some car models handle dehumidification automatically in auto mode, but I still prefer manual adjustments for peace of mind. Remember to check the air conditioning system regularly to prevent pipe blockages from affecting performance. In short, AC isn't mandatory, but it's much safer to turn it on when dealing with fogging issues.

[DiBeau]

In winter, the use of the AC function in a car depends on personal habits and the environment. During my daily commute, I rarely turn on the AC actively because the warm air is sufficient for heating, and using the AC increases engine load and fuel consumption. However, on rainy, snowy, or damp and cold days, I occasionally turn on the AC to help dehumidify and prevent fogging on the windows, which can obstruct visibility. The design of the air conditioning system allows the warm air and dehumidification to work together, and some new cars can even automatically detect humidity and adjust the AC. I believe that developing this habit can extend the lifespan of the air conditioning system, such as turning off all switches when parking to reduce wear. The key is to balance comfort and energy efficiency—avoid using the AC when it's unnecessary.

[Lamar]

When using the car's heating system in winter, the AC button is not for heating but assists in dehumidification. From my experience driving various models, the primary heat source in winter comes from the heater core, while activating the AC compressor increases fuel consumption. On clear days without fogging, it can be turned off; however, during high humidity, I turn on the AC for quick dehumidification to prevent obstructed visibility from fogging. The climate control system usually manages this intelligently, but manual control can also achieve the desired effect. Simply put, be flexible in handling it with safety as the top priority.