When selected, it helps cool down the interior with maximum efficiency. Instead of continuing to draw fresh air from outside the vehicle, Recirculation sends already cooled interior air back through the air conditioning system, cools it further and sends it back into the interior.
With Auto Climate Control, pressing the AUTO button will turn off the Recirculation button indicator, but the system may engage it as needed for best climate control performance.
Recirculation can also be used to keep harmful or smelly exterior air out of the cabin.