Do window air conditioners affect a room's humidity level?

Yes, window air conditioners remove humidity in the air. The evaporator coils located in the front of the air conditioner grow cold during normal operation. As the warm, moist air in the room comes in contact with the cold evaporator, the air's moisture condenses and attaches to the evaporator coil. As more moisture condenses, moisture on the coil drips into the base of the air conditioner where it is evaporated to the outside of the home.