Should You Use Internal or External Air Circulation When Warming Up Your Car in Winter?

[EmilianoRose]

In winter, alternate between internal and external air circulation when warming up your car. Initially, use internal circulation to retain the initial heat. Once the temperature rises, switch to external circulation, which utilizes the car's electric heating grid to warm the fresh air. A few minutes before parking, turn off the heater and switch to external circulation to allow the temperature of the air conditioning pipes to align with the outside temperature, ensuring relative dryness within the air conditioning system and preventing bacterial growth. Internal circulation is primarily used to effectively block external dust and harmful gases from entering the car, such as when driving through areas with smoke, dust, strong odors, or in heavy traffic, to prevent harmful exhaust emissions from the vehicle ahead.

[StAngelo]

Having driven for many years, I've learned that winters in the north are particularly cold, and I always prioritize using the external air circulation. When the car is first started, the interior temperature is low, and the windows are prone to fogging up. The external circulation quickly introduces outside air—though it's a bit chilly, it effectively removes fog, ensuring clear visibility for safer driving. After parking and letting the engine warm up for a few minutes, when the interior becomes a bit warmer, I switch to internal circulation to lock in the temperature, enhancing comfort. Remember to keep the air vents clean to prevent dust buildup, which can hinder airflow. Using only internal circulation for extended periods can trap carbon dioxide, making you drowsy, so it's important to stay alert while driving. Developing this habit has significantly reduced winter driving hassles and can even extend the lifespan of the air conditioning system.

[McGraham]

I prefer the car to warm up faster, so recirculation mode is my go-to. In winter, as soon as I get in the car, I turn on recirculation to let the warm air circulate and heat up the interior, preventing heat waste. Within minutes, the cabin becomes nice and toasty. Using fresh air mode draws in cold air from outside, which slows down the temperature rise and consumes more fuel—especially inefficient for short commutes. Just remember to briefly switch to fresh air mode when windows fog up to balance it out. From experience, using recirculation during the initial heating phase works best; consider fresh air only after achieving stable warmth. Regularly checking the cabin air filter is also crucial to avoid poor air quality during recirculation, which could affect health.

[OTessa]

When driving with kids in winter, I prioritize air quality, so I prefer the fresh air mode (external circulation). It brings in fresh air, reducing odors and CO2 buildup inside the car, especially helpful for preventing motion sickness on long trips. Recirculation heats up faster but makes the air stuffy, easily causing discomfort. In the morning, use recirculation first to warm up the car quickly, then switch to fresh air mode to replenish oxygen. Adjust based on temperature to prevent window fogging that blocks visibility. Make it a habit to service the AC regularly to ensure proper system function.