What is the Difference Between the Internal and External Circulation of a Car's Air Conditioning?

[AvaDella]

The difference between the internal and external circulation of a car's air conditioning: 1. Symbols for internal and external circulation: The internal circulation symbol is a circular arrow inside the car graphic; the external circulation symbol is an arrow entering the car from outside. 2. Operation methods of internal and external circulation: In internal circulation, air only circulates inside the car without exchanging with the outside air; in external circulation, the air inside the car is connected with the outside air, with outside air flowing in from the front intake and out from the rear exhaust. The use of internal and external circulation should be flexible, chosen based on the driving environment: 1. During traffic jams: Use internal circulation for the air conditioning, as external circulation would draw exhaust fumes from outside into the car. 2. General air conditioning cooling: Use internal circulation to quickly lower the temperature inside the car. Once the temperature stabilizes, appropriately switch to external circulation to exchange air with the outside. 3. Cooling the car after outdoor exposure to sun: First use external circulation for the air conditioning, and you can also open the windows to speed up heat dissipation. After a few minutes, close the windows, switch to internal circulation, and turn on the cooling.

[LilahFitz]

When it comes to the car air conditioning's recirculation and fresh air modes, after driving for so many years, I think the main difference lies in the air source. Recirculation means the AC only circulates air inside the car, repeatedly blowing cooled or heated air. The advantage is quicker cooling in summer to save AC effort and faster warming in winter. Fresh air mode draws new air from outside, instantly refreshing the cabin when there are odors or stuffiness, like preventing exhaust fumes from entering in tunnels. But note that prolonged use of recirculation can make the air stuffy, leading to windshield fogging, especially noticeable in rain or snow—recommend using fresh air mode combined with defogging. Many modern cars have automatic AC that intelligently switches between modes, making it hassle-free and energy-efficient. Overall, switching based on road and weather conditions enhances comfort and safety—like using recirculation in traffic to avoid exhaust or fresh air on highways for ventilation.

[OJourney]

I'm particularly concerned about in-car air quality, and the difference between recirculation and fresh air modes is significant. Recirculation keeps the AC circulating air within the cabin, blocking external pollutants - ideal for pollen season or polluted areas. Fresh air mode draws outside air in, helping dilute CO2 buildup that can cause drowsiness. But in areas with poor air quality, fresh air mode may introduce more harmful substances. My strategy is to prioritize recirculation in urban traffic to block exhaust fumes, then quickly switch to fresh air mode in suburbs or clean-air areas - this keeps me more comfortable. Don't forget regular cabin filter replacements; they improve airflow and reduce allergy triggers. Smart automatic AC systems intelligently balance both modes based on temperature, ensuring both safety and comfort during drives.

[SanViolet]

From an energy-saving perspective, the difference between recirculation and fresh air modes is quite significant. When using air conditioning, recirculation mode only circulates air within the car, providing higher cooling/heating efficiency and faster fuel/power savings. Fresh air mode has to process external hot or cold air, resulting in relatively higher energy consumption. In summer when you want quick cooling, first use recirculation mode, then switch to fresh air mode for ventilation after temperature drops. However, prolonged recirculation use worsens cabin air quality and may cause window fogging - it's recommended to combine with defogger function when switching. Environmentally, proper usage can reduce emissions, like maintaining airflow with fresh air mode on highways. Overall driving becomes more economical and comfortable.