Refrigerant is the chemical fluid that carries heat through an air conditioner or heat pump, absorbing heat as it evaporates in the indoor coil and releasing it as it condenses outdoors. Under EPA rules issued through the AIM Act, new residential systems are moving from R-410A to lower global-warming-potential refrigerants such as R-454B and R-32.
Why it matters to you
Refrigerant circulates in a sealed loop and is not used up, so a system that needs repeated top-offs has a leak. Older systems built for R-22, which can no longer be produced or imported in the U.S., can only be recharged from recovered or reclaimed supply.
Practical guidance
Ask for a leak search and repair before any recharge, and check which refrigerant your system uses on the outdoor unit's data plate. Refrigerants are not interchangeable, so an R-410A system cannot simply be refilled with R-454B.