Is it better to use internal or external air circulation when turning on the air conditioning?

[VeraDella]

Generally, internal air circulation is more commonly used when driving with the air conditioning on. Here are the specific introductions to internal and external air circulation in cars: 1. External air circulation: External air circulation refers to drawing air from outside the car, directing it into the air conditioning system for heating or cooling, and then blowing it out through the vents. Essentially, external air circulation replenishes fresh air and improves the air quality inside the car. It is used for defrosting in winter or defogging in summer because the air drawn from outside is richer in oxygen and drier, making it more effective for these purposes. 2. Internal air circulation: Internal air circulation draws air from inside the car, creating a cycle of air flow within the vehicle. The main function of internal air circulation is to effectively prevent external dust and harmful gases from entering the car. It helps the car warm up faster in winter and cool down quicker when the air conditioning is on in summer. It can also be used during smoggy days. Internal air circulation maintains the air inside the car, helping to better preserve the interior temperature.