A method, apparatus, system, and computer program product for managing a vapor cycle machine. Data is received for the vapor cycle machine in an aircraft. The data comprises a pressure, a temperature, and a speed for a set of compressors in the vapor cycle machine. A ratio of the pressure to the temperature is determined for the set of compressors that ran during a flight of the aircraft. A set of actions is performed when the ratio of the pressure to the temperature for the set of compressors that ran during the flight of the aircraft exceeds a threshold more than a selected number of times over a range of flights for the aircraft.