When window air conditioner is on should air exhaust be open or closed?

When the Exhaust is open the air conditioner will use outside air for part of the air it cools then blows into your house. with it closed it uses only air inside the house.















The trade off is that you'll get cooler air with it closed because the unit is using air that is cooler to begin with. However a house that is shut up tight is going to be stale.