The condenser is the high-pressure equipment of the system when the outdoor heat exchanger is cooling (the cold and warm heat pump type is the low-pressure equipment when heating), which is installed between the compressor exhaust port and the throttling device (capillary or electronic expansion valve). The high-temperature and high-pressure gas (Freon) discharged from the air conditioning compressor enters the condenser and is cooled through copper tubes and aluminum foil. The air conditioners are equipped with axial flow cooling fans, which are air cooled, During the cooling and condensation process, the refrigerant will be transformed from gas to liquid with constant pressure and low temperature.

In theory, the process of refrigerant change in condenser can be regarded as isothermal change process. In fact, it has three functions. First, the air takes away the overheated part of the high-temperature air-conditioning refrigerant gas sent by the compressor, making it become dry saturated steam; Second, liquefaction is carried out under the condition of constant saturation temperature; Third, when the air temperature is lower than the condensation temperature, the liquefied refrigerant will be further cooled to the same temperature as the surrounding air to play a cooling role.