In winter, should the heating use internal or external air circulation?

[LaGemma]

In winter, it is recommended to use the internal air circulation when turning on the heating, as this can quickly raise the temperature inside the car. However, when driving at high speeds, it is advisable to periodically switch the air conditioning to external air circulation mode to keep the air inside the car fresh. Below are the differences between internal and external air circulation: 1. The purpose of internal air circulation is to prevent dust and odors from being drawn into the car through external circulation. Therefore, a control system is set up to close the external air circulation ducts, blocking out polluted air from outside. At the same time, turning on the heating with internal circulation can quickly increase the temperature inside the car. 2. External air circulation draws in air from outside the car, processes it, and then blows it into the car's interior. This type of circulation has the advantage of constantly refreshing the air, replacing the stale air inside the car with fresh air. If the window glass fogs up, using external circulation can quickly eliminate the fog.