JPS6114003B

PURPOSE:To ensure that automobile instruments can be operated with small forces by a method wherein a diaphragm utilizing negative pressure is used for operating instruments such as an air mixing damper and a hot-water amount control valve, and a manual operating member of a control panel unit is so disigned as only to operate a negative-pressure change-over switch. CONSTITUTION:With a knob 12b gripped and an operating lever 12 moved leftward, for example, under the condition where a hole 6k of a rotary plate 6b of a negative-pressure change-over switch 6 is located between grooves 6f and 6g of a rotary plate 6a laid upon the plate 6b, the plate 6b is rotated counterclockwise through a wire cable 10, and the hole 6k is communicated with the groove 6f in communication with a negative-pressure source. Therefore, the negative pressure fed to a diaphragm device 4 is increased, an arm 4a is attracted, and the plate 6a starts rotating together with a damper 2. With the hole 6k relocated between the grooves 6f, 6g as a result of the rotation, the device 4 is stopped.