PURPOSE: To enable to perform control of a fan coil unit by making automatic decision in air conditioning, by making decision of air conditioning effect by detecting correctly the temperatures of cold and hot water and the inside of a room.

CONSTITUTION: A fan coil unit 8 is provided with a suction port 9 and a blow-off port 10, an inlet pipe 13 is provided with a hot and cold water temperature sensor 14 and the suction port 9 is provided with a room temperature sensor 17. The cold and hot water temperature sensor 14 detects the cold and hot water temperatures for cooling and heating and voltage conversion of the temperature is made by a temperature-voltage conversion circuit 22. The room temperature sensor 17 detects the room temperature at the time of the cooling and the heating and the voltage conversion of the temperature is made by a temperature-voltage conversion circuit 18. An output is decided by a temperature difference decision circuit 23 of the cooling and the heating as compared voltage of signals of the cold and hot water temperature sensor 14 and the room temperature sensor 17 with eacg other. In other words, when the decision circuit 23 shows an instruction signal of cooling and heating, an output signal from a room temperature control circuit 19 is put out from an output control circuit 21 as it is and when the same circuit 23 shows a forbidden signal of operation the same signal is applied to an output 24 from the output control circuit 21. With this construction, change-over of the cooling and the heating and operation of a blower 11 of the fan coil unit are performed.