perform a refrigerating cycle as shown in fig2 one end of a duct 37 is in communication with discharge opening 29 and the other end thereof is closed a plurality of diverging openings 39 41 43 are formed in the portions of duct 37 corresponding to first second and third chambers 13 15 and 17 a plurality of terminal units 45 47 and 49 are connected between the plurality of diverging openings 39 41 43 of duct 37 and first second and third chambers 13 15 and 17 to supply air from internal unit 21 to each chamber 13 15 17 each terminal unit 45 47 49 includes a damper 51 53 55 disposed in the pass thereof to control the flow of air fed from internal unit 21 to each chamber 13 15 17 the opening degree of each damper 51 53 55 is controlled by a motor not shown between the fully opened position and the fully closed position however in a practical operation a flow of air fed from internal unit 21 is controlled between the fully opened position and a minimum opened position of the damper the opening degree of which is fourty or fifty percent of its fully opened degree fully opened position a flow of air fed from internal unit 21 is not substantially controlled between the minimum opened position and the fully closed position of the damper terminal units 45 47 and 49 respectively include an air volume sensor 57 59 61 to detect the amount of air fed from internal unit 21 to each chamber 13 15 17 through duct 37 chambers 13 15 and 17 are respectively provided with a remote control unit 63 65 67 thus the temperature in.