Should the internal or external circulation be used when turning on the cold air?
3 Answers
When turning on the cold air in a car, the external circulation should be used. The air conditioning system has two circulation modes: internal and external. Here is relevant information about internal and external circulation: 1. Internal circulation means the air inside the vehicle is recirculated, i.e., the air coming out of the vents is from inside the cabin, which is sealed and not connected to the outside atmosphere. External circulation means outside air enters the cabin, so the air from the vents comes from outside the vehicle, and the cabin is not sealed, being connected to the outside atmosphere. 2. Internal circulation refers to the air blown by the fan circulating only inside the vehicle. Since no outside air is involved, it has the advantages of saving fuel and cooling (or heating) quickly, but the disadvantage is that it does not facilitate air renewal inside the vehicle. External circulation means the fan draws fresh air from outside into the vehicle, which ensures better air quality inside the cabin but cools (or heats) slightly slower and consumes more fuel.
When turning on the AC, I find it more practical to use the recirculation mode first, then switch to fresh air mode after the cabin temperature drops. After all, recirculation allows the cabin air to repeatedly pass through the AC for cooling, achieving faster cooling effects. On a stuffy summer afternoon, running recirculation for 2-3 minutes first makes it easier for the AC to cool down the entire cabin without overworking. However, be careful not to use recirculation continuously, as poor air circulation may cause dizziness or stuffiness, especially when elderly or children are in the car. After some time, switch to fresh air mode to introduce outside air, maintaining coolness while avoiding breathing issues. Additionally, if outdoor air pollution is severe, such as during city traffic jams, you can appropriately extend recirculation time to reduce exhaust fume inhalation.
From an energy-saving perspective, using the recirculation mode with the air conditioning on can significantly improve cooling efficiency, saving both fuel and money. When the AC compressor is running, cooling the existing air inside the car is much easier than continuously cooling the hot outside air, reducing the engine's workload and overall fuel consumption. However, the fresh air mode is also necessary at appropriate times. For example, during long-distance driving, using recirculation continuously for several hours can increase the carbon dioxide concentration inside the car, potentially causing drowsiness and affecting safe driving. It is recommended to use recirculation for the first 5-10 minutes after turning on the AC to speed up cooling, then periodically switch to fresh air mode for ventilation. During pollen season or when air quality is poor, adjust flexibly to prioritize health protection.
