The study of differences between Refrigerant 12 and Refrigerant 134a in automotive air conditioners has led to new methods of presenting refrigerant data. Pressure-enthalpy curves generated on a PC computer with high resolution graphics assist engineers in understanding thermodynamic behavior. The air-conditioning system data is plotted on these curves and animated as the system changes conditions. This visual effect is also used with the temperature-entropy diagram. Graphs of coefficient of performance, (COP), irreversible heat loss, and availability complete this study of the first and second laws of thermodynamics for refrigeration cycles.