What is the use of the car's external circulation mode?

[DiCody]

External circulation mode is used in the following situations: 1. When you first buy a new car, turning on this mode helps quickly eliminate harmful gases and odors inside the vehicle. 2. During cooling, sometimes this mode needs to be activated to rapidly circulate air between the interior and exterior, serving as a ventilation and filtration function. 3. On rainy days, it enables quick ventilation without allowing rainwater to enter the car, and also helps eliminate window fogging. Here is a brief introduction about external circulation: (1) External circulation mode refers to the car's air conditioning system opening to allow airflow with the outside air, absorbing external air for circulation. (2) The disadvantage of external circulation mode is that when harmful gases enter the vehicle, they can cause harm to the health of the driver and passengers.

[DelValentina]

I usually use the external air circulation mode most often for defogging, especially when the front windshield fogs up in winter. Turning on the external circulation directly introduces dry outside air, which quickly and naturally removes the fog. Another situation is when stuck in traffic next to a truck emitting black smoke—immediately switch to internal circulation and then back to external when the air is cleaner. I always remind my novice driver friends to switch to external circulation mode periodically during long trips, otherwise, the high concentration of carbon dioxide in the car can easily cause drowsiness. Additionally, when starting the air conditioning, it's best to run the external circulation for a few minutes first to quickly dissipate the new car smell. Finally, a reminder: it's best not to use external circulation during sandstorms or when passing by a landfill.

[NicoleAnn]

I find that using the external air circulation is particularly suitable for two scenarios: one is during rainy days when opening the windows would let rainwater in—turning on the external air circulation provides ventilation without soaking the seats; the other is when traveling with children, as kids are prone to motion sickness, and switching to external air circulation for fresh air helps a lot. I remember one summer when I parked outdoors, the car thermometer showed 62 degrees. I ran the external air circulation for five minutes before turning on the AC, and the cooling effect was noticeably better. The most practical use of external air circulation is dealing with odors, like hot pot or cigarette smells—just ten minutes usually clears them out. However, it's best to avoid using it on smoggy days, especially when the air quality index exceeds 150, as it's bad for the respiratory system.

[KinsleyLynn]

Seven or eight years of driving experience have taught me that the external air circulation is like the respiratory system of a car. Before entering a tunnel in summer, I always turn it on in advance to avoid fogging on the windows caused by sudden temperature changes. The difference is especially noticeable on highways—with external air circulation on, tire and wind noise are significantly reduced, and the air conditioning load is lighter. The most useful scenario is during mountain drives; letting natural air in through the external circulation feels much more comfortable than using the AC. Occasionally, if I forget to close the sunroof and get caught in the rain, leaving the external circulation on overnight can basically dry out the moisture. Of course, it should be used with caution during pollen season—once, after just half an hour with it on, I couldn’t stop sneezing.

[Natasha]

The external circulation mode is a road trip essential! My last drive along the Sichuan-Tibet highway proved it: running AC in high-altitude areas guzzles fuel, while using external circulation for natural ventilation shows noticeable fuel savings. Driving through forested sections with external circulation brings pine fragrance straight into the cabin - more refreshing than any aromatherapy diffuser. In city traffic jams, external circulation helps ease stuffiness, but remember to switch it off when passing chemical plants. I've found that combining heater with external circulation defrosts windows faster than using defroster alone in winter. Pro tip: maximize external circulation usage during the first month with a new car - it's remarkably effective for dispersing formaldehyde.

[SiennaLynn]

As a seasoned driver, here are a few clever uses of the external air circulation: When you're afraid of insects getting in while enjoying the sunroof during spring outings, turning on the external air circulation ensures both ventilation and safety; Driving by the seaside often leads to salt frost on the windows, which can be quickly cleared by using the external air circulation along with the wipers; Lingering smells of durian or stinky tofu in the car? Just 20 minutes with the external air circulation will take care of it. I particularly love turning on the external air circulation right after a rain when the sun first comes out—the earthy-smelling air is incredibly soothing. Here's a handy tip: Before turning on the AC after your car has been baking in the summer sun, use the external air circulation to expel the 70-degree hot air first, and it will cool down twice as fast. But remember, never turn on the external air circulation right behind a water sprinkler truck—don't ask me how I know...