While most people don’t associate cool air with liquid, that’s exactly what refrigerant is. At least for a good part of the time. It’s really a chemical compound that exists either in a liquid or gaseous state inside the copper coils of your A/C system. There are different types of refrigerant gas cylinders used today, but they all generally work the same way. The refrigerant moves between the indoor and outdoor units of your A/C and transitions between its liquid and gas states.