Handbook 752 Air Conditioning and Climate Control A/C System The basic A/C system contains components to push refrigerant through a closed system in order to extract heat out of the vehicle interior and transfer that heat to the outside air. This cycle continues constantly until the vehicle’s interior reaches a set temperature. Inside the A/C system, the refrigerant changes from a liquid to a gas and then back to a liquid. As we shall see, this phase change is what helps remove heat from the air circulating inside the vehicle. 12 Technical Training