Should You Use Internal or External Air Circulation When the Car Interior is Humid?
2 Answers
Use external air circulation to dehumidify the car interior. Internal circulation means the air conditioning system is closed off from outside air and only recirculates the air inside the car, while external circulation allows the air conditioning system to draw in fresh air from outside the car, promoting better air flow and faster moisture removal. Here are some related details: Methods for dehumidifying the car interior: 1. Use the air conditioner in cooling mode: Turn on the AC and switch to external circulation mode to promote air exchange between the inside and outside of the car, gradually eliminating moisture. 2. Place desiccants inside the car: Items like activated charcoal or lime can be placed near the cooling evaporator where condensation tends to form, while desiccants can be placed in other corners. 3. Turn on electrical devices: The heat generated by operating electrical devices can help dehumidify the interior. 4. Park in sunlight: This is the simplest and most effective method for dehumidification. Precautions when using external circulation: 1. Avoid using external circulation immediately after turning on the AC or heater, as it may take longer for the interior temperature to reach the set value, increasing engine load and fuel consumption, and potentially shortening engine lifespan in severe cases. 2. Do not use internal circulation for too long; periodically switch to external circulation to ventilate the cabin and maintain air flow, preventing discomfort during driving.
I used to experience a damp interior when driving in rainy weather, with windows fogging up easily and blurred vision posing a real danger. Back then, a friend suggested trying the recirculation mode, but it didn’t help much—the humidity couldn’t escape and instead accumulated even more. Later, I figured out the trick: using fresh air mode is the smarter choice because it introduces dry outside air, helping to dilute the moisture inside the car. Combined with the air conditioning’s dehumidification function, it quickly clears the fog. Remember, never use recirculation mode—it only cycles the internal air, leading to worse humidity buildup, especially in humid southern regions. Personally, I make it a habit to check the fresh air mode switch as soon as I get in the car. If I notice the interior is damp, I turn on the fan at high speed, and usually, the fog clears within minutes, making driving much safer. It’s also good practice to keep fresh air mode on regularly in humid weather—prevention is better than dealing with the aftermath.
