Do You Need to Turn on AC for Hot Air?
2 Answers
Hot air does not require turning on the AC. The warm air is generated by the engine's heat and circulated into the car through the air conditioning system, thereby increasing the interior temperature. If you turn on the AC switch while using the warm air, the compressor will also operate, which not only fails to improve the heating effect but also increases fuel consumption. The AC button controls the air conditioning compressor's switch. During summer, when the driver turns on the cold air, the AC button must be pressed simultaneously for the air conditioner to cool and circulate cold air inside the car. Drivers can turn off the AC switch during startup or rapid acceleration, as the air conditioning compressor is driven by the engine and consumes some of its power. Turning off the AC switch can prevent insufficient engine power.
I've been driving for almost ten years, and this is a question many new drivers ask. Simply put, you usually don't need to turn on the AC when using the heater, because the hot air in the car comes from the engine's heat, transferred to the cabin via the coolant—just turn the temperature knob to the hot setting. But why do experienced drivers sometimes say to turn on the AC? Mainly for dehumidification. In winter or rainy weather, when the air is humid, not using the AC can cause the windows to fog up, which is dangerous—blurred vision increases the risk of accidents. I’ve experienced it myself: driving on the highway in the rain when the windows suddenly fogged up. I quickly turned on the AC and the fan, and the air became much drier. For everyday driving, if there’s no fog or humidity, don’t use the AC to save fuel. But if there’s fog, turn it on—safety first. Remember, the AC is for dehumidification; the heat itself doesn’t rely on it.
