Recirculation is useful on very hot days because it helps the air conditioner cool the cabin faster. It can also help reduce odors, exhaust fumes, dust, and pollen when driving through traffic or polluted areas.
However, keeping it on for long periods can trap moisture inside the car and make windows fog up, especially in cold or rainy weather. If the cabin starts feeling stuffy or visibility decreases, switching back to fresh-air mode can help.
A good habit is to use recirculation temporarily, then allow fresh air back in when conditions improve. Replacing the cabin air filter regularly also helps keep airflow cleaner and the climate system working properly.
