Should You Use External or Internal Air Circulation for Car AC in Winter?

[DawsonLynn]

Whether to use external or internal air circulation for car AC in winter depends on the actual situation: 1. If you want to quickly heat up the car interior in winter, you can start the engine and drive normally for a while to warm it up. When the temperature gauge needle reaches the middle position, turn on the heater with internal circulation. Using internal circulation allows the AC to quickly cool or heat the car interior. This not only warms up the car quickly but also avoids putting a burden on the engine and saves fuel. 2. However, although continuous internal circulation keeps the car warm, the interior becomes a relatively sealed environment. Prolonged exposure to such conditions can lead to oxygen deprivation, so it's best to switch to external circulation every hour to draw in fresh air from outside. This air then passes through the AC evaporator or heater core to blow cold or warm air, respectively.