Do you need to turn on the AC in winter for cars?
3 Answers
In winter, you don't need to turn on the AC when using the car's heating system. The AC is the switch for the air conditioning compressor, which is essential for cooling in summer. However, the heating system utilizes the car's internal heat circulation and does not require the air conditioning compressor to be activated. To use the heater, simply adjust the air conditioning controls. Steps to turn on the car's heating system: When the car starts, the engine begins to warm up. Wait until the engine temperature gauge reaches the middle position, then turn on the heating system. Set the air circulation to external mode to expel the cold air from the car. After 2 to 3 minutes, switch the air circulation back to internal mode. When there is a significant temperature difference between the inside and outside of the car, the front windshield is prone to fogging. To prevent this, adjust the heating vents to direct airflow toward the windshield. Using the heating system does not consume extra fuel: The heat for the heating system comes from the engine's operation. When the engine's cooling system dissipates heat, a fan directs this heat into the car's interior, creating warm air. When the heating system is not in use, the fan stops, and the heat vents close, allowing the heat to dissipate into the atmosphere. Therefore, the car's heating system recycles waste heat and does not consume additional fuel.
I've noticed many car owners have misconceptions about using the AC in winter. In fact, you don't need to activate the compressor for heating in winter - the warm air comes from the engine's heat, so turning on the AC just wastes fuel. However, during rainy days or when windows fog up, using the AC becomes crucial. The compressor can quickly remove moisture, and combined with warm air, it can defog windows in just half a minute. My usual practice is to adjust based on weather: turn off AC to save fuel during dry sunny days; immediately press the AC button and turn on warm air when encountering rain/snow or fog caused by passengers' exhaled moisture. Remember, you can turn off the AC after defogging and keep just the warm air on. For cars with automatic climate control, simply pressing AUTO is the most convenient option.
This issue stems from how air conditioning works. The heating system utilizes waste heat from the engine and isn't related to the compressor. However, defogging requires the compressor for dehumidification, especially when interior humidity is high. Living in the Jiangnan region where winters are humid, if I don't turn on the AC, the windshield immediately fogs up, obstructing visibility. My routine is: start the engine to warm up first, switch to external circulation mode, and only turn on the heater after the coolant temperature gauge needle moves. If fogging occurs then, promptly pressing the AC button doubles defogging efficiency. Once the fog clears, turning off the AC ensures both safety and fuel economy. Drivers in arid northern regions might not need this hassle, but southern car owners largely rely on this technique for anti-fogging.
