Should You Press the A/C Button When Turning on the Heater?

[JakeMarie]

When turning on the heater in winter, there is no need to press the A/C button. More information about the A/C button is as follows: 1. The A/C button stands for Air-Conditioner, which is the cooling switch of the air conditioning system. When pressed, the A/C light turns on, controlling the engagement of the compressor's electromagnetic clutch. The compressor starts working, initiating the cooling cycle, which also increases fuel consumption. Therefore, the A/C button primarily controls the air conditioning's cooling function. 2. The main function of the car's A/C switch is to adjust and control the temperature, humidity, air cleanliness, and air flow inside the car cabin to maintain optimal conditions.

[LaVincent]

I've been driving for over a decade and encounter heating issues every winter. I've noticed many car owners don't understand the relationship between A/C and heating. In fact, the heat for warming comes entirely from the engine's coolant circulation. Once the water temperature rises, turning on the fan will blow out hot air, which has nothing to do with the air conditioning compressor. Therefore, under normal circumstances, you don't need to touch the A/C button when using the heater—pressing it actually wastes fuel because activating the compressor increases fuel consumption. However, I always turn on the A/C when driving in rainy weather because the compressor helps remove moisture, preventing the windows from fogging up. The same principle applies to defogging in summer, but in winter, the heater alone is sufficient without the A/C. If you're really afraid of the cold, just wear more layers instead of letting the compressor work unnecessarily.

[SanHarrison]

Regarding whether to turn on the A/C when using the heater, I think it depends on the specific situation. I've noticed while driving that the engine's own heat is sufficient for warming, making it unnecessary to activate the compressor. However, during a long-distance trip last time when I encountered heavy fog and all the windows were covered with condensation, I tried turning on the A/C along with the heater, and the defogging effect was remarkably fast. Actually, the main function of the A/C is dehumidification; the compressor's operation condenses moisture in the air into water droplets and expels them. But when using the heater normally, avoid keeping the A/C on continuously, as it can significantly increase fuel consumption, especially noticeable during traffic jams. Remember, there are dedicated vents below the windshield; adjusting the airflow direction there is much more effective than using the side window vents.

[Judy]

When I first started driving, I was also puzzled about whether to turn on the A/C, shivering from the cold in winter. Later, I realized that you don’t need to press that button for heating because the warm air comes from the engine’s waste heat and has nothing to do with the compressor. Once during heavy snow, I turned on the A/C and noticed the fuel consumption skyrocketing before realizing my mistake. Now, I simply turn the temperature knob to the red zone and set the fan to level two for warmth. However, when the windows fog up, I still need to turn on the A/C—a wet towel can’t clear the glass as fast. My tip is to check the dashboard when using the heater: as long as the A/C indicator isn’t lit, you’re doing it right.

[OAlice]

As someone who frequently drives long distances, I have profound experience with using the heater. During my trip from Heilongjiang to Hainan, I tested various methods and concluded that in 90% of cases, there's no need to turn on the A/C. Once the engine coolant reaches operating temperature, the heat from the heater core is sufficient to warm the cabin, and using the A/C wastes about 10% of fuel consumption. However, it's essential to turn it on during rainy days as the compressor's dehumidification function keeps the windshield clear. Also, new car owners should note that some automatic climate control systems default to activating the compressor, so remember to turn it off manually. I've found that setting the temperature above 22°C and turning off the A/C actually feels more comfortable and prevents dry mouth.

[Anna]

I pay close attention to the humidity inside the car, so I'm particularly mindful of A/C usage when using the heater. Normally, I simply turn off the A/C and use the heater since the compressor consumes fuel and dries out the air. However, during the damp and cold weather in the south, I intermittently turn on the A/C for a few minutes because the dehumidified warm air prevents my glasses from fogging up and feels more refreshing. I remember last time when I set the temperature knob to 26°C but felt stuffy—turning off the A/C immediately made it much more comfortable. Now, I've developed a habit of turning off the A/C first after starting the car, then turning on the heater, and only temporarily activating the A/C when defogging is needed.