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What Is The Ventilation Lever For?
The Ventilation Lever on your air conditioner opens and closes a vent to the outside, and lets you bring fresh, outside air into your room.
To open the vent and let outside air into the room, push the Ventilation Lever to the right. To close the vent, push the Ventilation Lever to the left.
Although it is somewhat more efficient to keep the vent closed when you run the air conditioner, where you set the Ventilation Lever when you run the air conditioner is a personal preference. Try it both ways and see which way you like best.