If you are closing some of your air conditioner’s vents, in rooms that aren’t in use, DON’T! It turns out that will cost you MORE money in the long run! When you close a vent it forces air out of small spaces into the crawl space or attic. This can cut the airflow throughout your home and reduces your system’s efficiency by 20%. When you keep all the vents open your air conditioning unit doesn’t work as hard so you’ll get more cool air in every room.