Should You Use External or Internal Air Circulation When Turning on the Heater in the Car During Winter?

[StJohn]

When turning on the heater in the car during winter, start with internal air circulation and switch to external air circulation once the car is warm. It is recommended to primarily use internal air circulation with occasional external air circulation, alternating between the two. This ensures the car stays warm while preventing a rise in carbon dioxide levels inside the car, which could affect driving safety. For long-distance trips, it is advisable to use external air circulation; in heavy traffic, switch to internal air circulation; and in dusty areas, use internal air circulation. To quickly heat up the car in winter, start the engine and drive normally for a while to allow the engine to warm up. Once the temperature gauge needle reaches the middle position, turn on the heater with internal air circulation. Using internal air circulation helps the air conditioning system rapidly cool or heat the car interior. This not only warms up the car quickly but also reduces engine load and saves fuel.