Most vehicles have a recirculation button with the AC controls in their cars. But many of us are unsure when to use it.
Well, the easy answer is to use it in the summer and turn it off in the winter.
The recirculation button simply takes the air from inside the car and recirculates it in the cabin instead of pulling fresh air from outside. On days like today when it is miserably hot outside, if you do not recirculate the cooler air in the cabin, then your AC system is pulling hot air from outside and trying to cool it. Using the recirculation feature will get your car cooler and will decrease the wear and tear on your AC system.
On a side note, if your car has been baking in the sun, it's better to roll the windows down and turn recirculate off for the first minute or two, in order to get rid of the super hot air inside the car before turning recirculate on.
Also, any time you are stuck in traffic (summer or winter) be sure to use recirculation. If you are pulling air from outside, then you are pulling in all the pollutants and carbon monoxide from all of the traffic around you.
Studies show that recirculating your AC can cut down on the pollutants entering your vehicle by 20% when stuck in traffic!