Cooling system

A reduction in the running costs of a heating and cooling system that uses solar heat, which combines a solar thermal collector and an absorption refrigerator, is achieved by means of a cooling system for cooling a heating medium, wherein: a solar thermal collector for collecting heat energy from at least the sun, an absorption refrigerator, a means for detecting the specific enthalpy of the outside air or the wet-bulb temperature of the outside air, a means for detecting the amount of direct solar irradiance, a means for detecting the cooling load of the heating medium that provides cooling, a means for detecting and measuring the pressure inside the solar thermal collector, and a pressure adjustment means for adjusting the pressure inside the solar thermal collector are provided; and the pressure inside the solar thermal collector is changed according to the specific enthalpy of the outside air or the wet-bulb temperature of the outside air, the amount of direct solar irradiance, and the cooling load of the heating medium that provides cooling.