what's an air conditioner?
Think of it as a chiller (only for the inside air and not your aquarium)!
I think I've shared this before, but the large corporate office building, where I go when I'm not working from home, doesn't have centralize heat. It has central air and on the few days when heat is necessary, there are heat strips at each vent that heat the central air. Because of the limited use, it apparently is cheaper to heat the a/c than to install a real heater.