The Cooling Pack, or Air Condition Pack, is an air cycle refrigeration system that uses the air passing through and into the airplane as the refrigerant. This is accomplished by a combined turbine and compressor machine, called Air Cycle Machine (A.C.M.), valves for temperature and flow control, and heat exchangers using outside air to dispense waste heat. The air condition pack provides essentially dry, sterile, and dust free conditioned air to the airplane cabin at the proper temperature, flow rate and pressure to satisfy pressurization and temperature control requirements.