| 摘要 |
PURPOSE:To defrost automatically by limiting/halting the supply of refrigerant to an indoor unit when a frosting signal is input from a temperature sensor of a cooling side indoor unit in heating operation mode during simultaneous cooling and heating operation. CONSTITUTION:Assuming that indoor units 11 and 12 are called for to perform heating operation while an indoor unit 13 is demanded to perform cooling operation, heating mode is selected since heating load is greater than cooling load. As a result, a two way valve 23 is closed while a two way valve 26 is opened so that an outdoor heat exchanger 3 may serve as a vaporizer where high temperature discharged refrigerant from a compressor 1 is introduced into the indoor units 11 and 12 by way of a valve circuit of a multi-control unit B and returns by way of flow rate control valves 14a, and 14b and a heating expansion valve 4. Moreover, a part of the refrigerant after the heating is introduced into the indoor unit 13 by way of a flow rate control valve 14c and a cooling expansion valve 15. When frosting on an indoor heat exchanger 13a is detected with a temperature sensor 34c, a control means 8b closes the flow rate valve 14c. It is, therefore, possible to defrost automatically and maintain a sufficient cooling capacity as well. |
