Most vehicles have a recirculation button with the air conditioning controls in their cars. You may be questioning on when to use it; let's tell you when!
The best time to use the circulation button is during the summer on very hot days. The circulation button takes the air from inside the vehicle and recirculates it in the cab of the vehicle instead of pulling the hot air from outside. When it is very hot outside and the recirculation button is not on, it is pulling the hot air from outside and trying to cool it. When the recirculation button is on, it pulls the cooler air from inside. Using the recirculation function will help keep the car cooler and keep the wear and tear down on your air conditioning system. If the vehicle has been sitting in direct sunlight it is best to roll the windows down and wait to turn on the recirculation function until the vehicle cools down.