Should the A/C be Turned On for Heating?
2 Answers
In winter, there is no need to press the A/C button when using the car's heating system. Activating the A/C button while using the heater in winter has no effect on warming the car. The meaning of the A/C button in cars: "AC" is the abbreviation for "Airconditioning" in English, which refers to the air conditioning device. Pressing the "AC" button starts the air conditioning system to adjust the temperature according to the set value, while turning it off means only the air blower operates, with the temperature adjustment mechanism inactive. When using the heating system: In vehicles, since the heating function of the car's air conditioning system is achieved through the heat from the engine's cooling water and the heating wires for the windshield, the A/C button solely represents the cooling function. In A/C mode, the car's air conditioning compressor remains operational, inevitably leading to increased fuel consumption and additional engine load. Therefore, when using the heating system, the A/C switch should be turned off to prevent the compressor from running, which would otherwise result in unnecessary fuel consumption during heating.
When I first started driving, I was curious whether to turn on the A/C for the heater. Actually, you usually don’t need to press the A/C button. This is because the heater directly uses the engine’s heat to warm the air, and turning on the air conditioning compressor only unnecessarily increases fuel consumption and adds extra load to the engine. In winter or cold weather, the main goal of using the heater is to stay warm, and the engine itself provides sufficient heat. However, in certain situations—like when the windshield fogs up or the air is very humid—turning on the A/C can help dehumidify the cabin faster, making it more comfortable and safer by clearing fog quickly for better visibility. I learned this in driving class and recommend keeping the A/C off most of the time to save fuel, only using it temporarily on foggy or rainy days. It’s also good to check the air conditioning system regularly to avoid wasting energy by keeping the compressor idle.
