SYSTEM FOR COOLING AND HEATING BY USING HEAT MEDIUM

PURPOSE: A cooling and heating system by using a heat medium is provided to defrost an air-cooling heat exchanger quickly and easily in using as a heat pump by adding a heat medium circulating circuit to a refrigerant circulating circuit, and to improve efficiency without changing the refrigerant circulating cycle by exchanging and transmitting heat with using the heat medium. CONSTITUTION: A cooling and heating system comprises a refrigerant circulating system having a refrigerant circulating circuit or more including an evaporator(1), a compressor(2), a condenser(3) and an expansion valve(7); a first heat medium circulating circuit(100) as a closed circuit circulating the evaporator and an air-cooling heat exchanger(40); a second heat medium circulating circuit(200) as a closed circuit circulating the condenser and an indoor unit(60); a third heat medium circulating circuit(300) as a closed circuit circulating the condenser and the air-cooling heat exchanger; a fourth heat medium circulating circuit(400) as a closed circuit circulating the evaporator and the indoor unit; and two pumps(P1,P2) or more installed in the first, second, third and fourth heat medium circulating circuits and selectively operated.