Central air conditioning is a common term used to describe most whole-home air conditioning systems. It replaces warm air with cool air that's been passed over cold coils, then pushes it into your living spaces. There are two different types of central air conditioners—split systems and packaged systems There are many different brands, models, and types of central air conditioning systems. Each model has unique features and energy efficiency ratings. However, all central ACs have one thing in common: They all use electricity, not gas.