What is the difference between the internal and external circulation modes of a car's air conditioning system?
2 Answers
The difference between the internal and external circulation modes of a car's air conditioning system lies in their working principles: Internal circulation mode closes the airflow passage between the interior and exterior of the vehicle. Without the fan running, there is no air circulation. When the fan is activated, the air drawn in comes solely from inside the vehicle, creating an internal airflow cycle. External circulation mode uses the fan to draw outside air into the cabin, maintaining an open air passage between the exterior and interior. The air blown by the fan originates from outside the vehicle, and even without the fan operating, airflow is naturally drawn into the cabin while driving. Car air conditioning, short for automotive air conditioning system, is designed to regulate and maintain optimal conditions for temperature, humidity, air cleanliness, and airflow within the passenger compartment. Its primary functions are to provide a comfortable environment for passengers, reduce travel fatigue, create favorable working conditions for the driver, and ensure driving safety.
As a seasoned driver with decades of experience, I fully understand the difference between recirculation and fresh air modes. Recirculation means the air inside the car circulates in a closed system, making the AC cooling or heating remarkably fast – the car cools down within minutes in summer, and heats up quickly in winter. But the downside is prolonged use leads to stuffiness as air stagnates, causing breathing difficulty and reduced concentration. Once during a summer road trip, I kept recirculation on for fuel efficiency but forgot to switch air sources, resulting in fogged windows that nearly caused a rear-end collision – a hard lesson learned! Fresh air mode draws outside air in, ventilating the cabin to eliminate odors and smoke while preventing windshield fogging. My routine is alternating between modes: using recirculation in city traffic to block exhaust fumes, and switching to fresh air on highways for better ventilation. Regular AC filter checks are also crucial to maintain proper circulation, significantly enhancing driving comfort and safety.
