Should the A/C Be Turned On in Winter for Car Air Conditioning?

[AnaLynn]

In winter, turning on the air conditioning is for heating, and there is no need to turn on the A/C. Below are the specific reasons and the principle of how the air conditioning provides warm air: Reasons not to turn on the A/C: The A/C light indicates that the air conditioning compressor is activated, which increases the engine load and fuel consumption. The warm air in a car's air conditioning system is provided by the engine coolant, so there is no need to turn on the A/C when using the heater in winter. Principle of how the air conditioning provides warm air: The warm air from the air conditioning is supplied by the engine coolant, which is the "water" in the radiator. Two hoses are connected from the engine coolant circulation loop to the heater core inside the air conditioning assembly. The warm air is delivered into the cabin by the fan, which transfers the heat from the heater core. Using the air conditioning for heating in winter neither affects the vehicle's power nor increases fuel consumption.

[IsabelleFitz]

Having driven for over a decade, I've learned there's real nuance to using A/C in winter. The key is assessing dehumidification needs – when the car's crowded or during rainy days, windows fog up easily. Engaging A/C rapidly removes moisture, proving far more efficient than relying solely on heated air. While compressor activation does consume some fuel, modern vehicles are intelligently designed to avoid summer-level strain. My routine is activating AUTO mode immediately; it automatically determines A/C necessity. During long drives in heavy fog, disabling A/C often leads to dangerous recurring fogging. However, in arid northern regions, the heater alone suffices without wasting that extra fuel.

[VanLouis]

During my last self-drive trip in Northeast China, I noticed an interesting phenomenon: at -20°C, the air conditioning compressor automatically protected itself and wouldn't start. This shows that modern vehicles intelligently control the A/C based on temperature. In daily driving, I pay special attention to windshield defogging effectiveness - turning on A/C clears fog about three times faster than using just the heater. Although compressor operation increases fuel consumption slightly, for an average family car it only adds about 20 yuan in monthly fuel costs. The potential accident costs caused by fogged windows are much higher. Also, remember that using recirculation mode in winter worsens window fogging - the best effect comes from combining A/C with fresh air mode.

[StIsabela]

A friend who works in auto repair told me that in winter, the compressor's workload is only one-third of what it is in summer. Many people assume that using the A/C consumes as much fuel as it does in summer, but in reality, the increase in fuel consumption during winter is less than 2%. The key point is that it helps balance the condensation caused by the temperature difference between the inside and outside of the car. I always keep a defogging spray in my car, but it only provides a temporary fix. Through practice, I’ve found that even in sub-zero temperatures, turning on the A/C speeds up defogging significantly. This is especially crucial during rainy or snowy days when picking up or dropping off kids, as sudden fogging on the windows can be very dangerous. Nowadays, I mostly keep my car in AUTO mode during winter, and by checking the tachometer at red lights, I can easily tell whether the compressor is running.