How to distinguish between internal and external circulation in Volkswagen CC?

[McCali]

The left indicator light on represents internal circulation, the right indicator light on represents smart internal circulation, and neither light on represents external circulation. Here are the specific introductions to the internal and external circulation of the car: 1. External circulation: External circulation refers to drawing air from outside the car, guiding it to the air conditioning system for heating or cooling, and then blowing it out from the air vents. External circulation essentially supplements fresh air to improve the air quality inside the car. Situations like defrosting in winter or defogging in summer require the use of external circulation because the air drawn from outside the car has higher oxygen content and is drier, making defrosting or defogging more effective. 2. Internal circulation: Internal circulation draws air from inside the car, forming an airflow circulation within the vehicle. The main function of internal circulation is to promptly and effectively prevent external dust and harmful gases from entering the car. It heats up the car faster in winter and cools it down quicker when the air conditioner is on in summer. It can also be used during smoggy days. Internal circulation means the air inside the car circulates, which helps maintain the interior temperature better.