Definition
Refrigerant is the chemical fluid that cycles through an air conditioner or heat pump, absorbing heat indoors and releasing it outdoors. Older systems used R-22 (now phased out and expensive), most current systems use R-410A, and the industry is transitioning to lower-global-warming refrigerants such as R-454B in new equipment.
Why this matters for your home
A system that's low on refrigerant has a leak — refrigerant isn't consumed like fuel. Simply 'topping it off' year after year wastes money and harms the environment. If your AC uses phased-out R-22, a refrigerant repair is often the moment replacement starts to make more financial sense.