Should the AC Button Be Turned On When Using the Car's Heater in Winter?
2 Answers
When using the car's heater in winter, there is no need to turn on the AC button. The warm air from the car's heater comes from the heat generated by the engine during operation, which is essentially a form of waste heat recycling. The working principle of the car's heater is as follows: after the engine's cooling system dissipates heat from the engine, the dissipated heat is blown into the car's interior by a fan to produce warm air. The method to turn on the car's heater in winter is to rotate the knob to the heating direction and turn on the fan switch to release warm air. The functions of the car's air conditioning system are: 1. To adjust and control the temperature, humidity, air cleanliness, and airflow inside the car cabin to an optimal state; 2. To provide a comfortable riding environment for passengers and reduce travel fatigue.
As a veteran driver with over a decade of experience, I initially thought pressing the AC button was necessary for winter heating, but later realized it's completely unnecessary. The car's AC button activates the compressor, while the heating actually utilizes waste heat from engine operation, much like residual warmth from a furnace. When the coolant temperature gauge reaches the midpoint, simply turn off the AC button and adjust the fan speed knob—warm air will naturally flow through the vents. Engaging the AC at this point would only waste fuel by needlessly running the compressor and placing extra load on the engine. However, there's one exception: when the windshield fogs up, using the heater alone is slow for defogging. Briefly activating AC with the heater for 2-3 minutes enables faster dehumidification to clear fog, after which the AC should be turned off. Additionally, for prolonged heater use, switching to external air circulation every half hour is recommended to prevent CO₂ buildup and drowsiness.
