AIR CONDITIONING APPARATUS

PROBLEM TO BE SOLVED: To provide an air conditioning apparatus that can control a refrigerant overheating degree at the exit of an evaporator to the most appropriate overheating degree regardless of operating requirements or construction requirements, and accomplishing an operation that provides maximum efficiency as a system.SOLUTION: The air conditioning apparatus includes: a computing part 32 for calculating the amount of circulation of refrigerant based on the rotational frequency of a compressor 5, and calculating the overheating degree of an evaporator exit based on the evaporation temperature detected by a third temperature sensor 43 and the refrigerant temperature detected by a fourth temperature sensor 44; an estimation part 34 for assuming a target overheating degree value based on the overheating degree, and estimating the suction pressure Ps' of the compressor 5 when the overheating degree changes to the target overheating degree value according to the amount of circulation of refrigerant and the overheating degree; and a control part 35 for comparing the suction pressure Ps detected by a pressure sensor 40 with the suction pressure Ps' estimated by the estimation part 34, changing the target overheating degree value based on the comparison result, and controlling the valve opening of an expansion valve 6 so that the overheating degree reaches the target overheating degree value.