An air conditioner for cooling and heating having multiple 4-way valves is provided to maintain a flow direction of a refrigerant in a regular direction for optimized heat transfer efficiency to exchange heat according to a flow of refrigerant and a flow of air so as to form a back flow regardless of an operation mode, thereby maintaining the best heat transfer efficiency all the time regardless of an operation mode. A compressor(10) compresses a refrigerant vaporized while absorbing heat. A main four-way valve(20) for operation mode conversion is arranged in front of a discharge port of the compressor. An outdoor heat exchanger(30) exchanges heat between a refrigerant and outdoor air. An expansion unit(40) expands liquid refrigerant of high temperature and high pressure. An indoor heat exchanger(50) exchanges heat between a refrigerant and indoor air. An auxiliary four-way valve(60) is arranged in front of a port of the outdoor heat exchanger of the main four-way valve to maintain a refrigerant flow direction in the outdoor heat exchanger regularly.
展开▼
