Winter Heating: Use External or Internal Air Circulation?
4 Answers
Whether to use external or internal air circulation for winter heating depends on the actual situation: 1. If driving on regular urban roads, internal circulation can be used; 2. If driving on highways or long-distance routes, it is recommended to use external circulation; 3. During traffic jams, external circulation should never be used, otherwise, the car may fill with exhaust fumes. Car air conditioning has both cooling and heating systems. Heating utilizes the car's own thermal cycle and does not require the compressor to work. The AC button activates the air conditioning cooling system, pressing it means the compressor starts working, primarily for cooling purposes.
When driving in winter, I adjust the air recirculation mode based on comfort. First, I turn on the external circulation to draw in fresh cold air for quick defogging, ensuring clear visibility and safety. Once the window fog dissipates, I switch to internal circulation for warmth, as it reuses the warm air inside the car, heating up quickly without consuming extra fuel, keeping the cabin cozy and pleasant. However, I avoid keeping the internal circulation on continuously for too long, as the air can become stuffy and drowsy-inducing, and it’s less hygienic. So, I briefly switch back to external circulation for a few seconds every 15 minutes to refresh the air, making the overall drive much more comfortable. I also adjust based on weather changes—for example, using internal circulation more in sub-zero temperatures and favoring external circulation on humid or rainy days to prevent fogging.
From an efficiency perspective, I'd first use the external air circulation to quickly defrost before switching to internal circulation. Introducing cold air via external circulation helps clear fog, then switching to internal circulation saves fuel—the engine heats less new air, achieving more efficient warming. For short winter drives, keeping internal circulation throughout provides sufficient warmth; but during long-distance driving, remember to briefly switch to external circulation every now and then for a few seconds to ventilate, preventing humidity buildup that could lead to condensation and fogging. This also avoids overloading the engine which affects fuel consumption. Based on my own tests, this switching method saves about 10% more fuel compared to using just one circulation mode, especially useful during cold snaps.
When using the heater, I prioritize health by first activating the external circulation to defog before switching to internal circulation. Internal circulation retains warmth but prolonged closure can lead to stale air—carbon dioxide buildup causes fatigue and increases fogging risks. I regularly switch to external circulation for 10 seconds to refresh the air and prevent dizziness; in crowded situations, I switch more frequently to minimize germ transmission. Additionally, I ensure the cabin air filter is clean to avoid inhaling dust and triggering allergies. This simple strategy ensures a safer and more comfortable drive.
