PURPOSE: To surely reduce an operated load to a compressor at the time of its starting, by open-close controlling a switch in accordance with a change of blowing air pressure from a cooling fan and open-close operating a suction valve in a main body of the compressor with a solenoid in relation to said switch.

CONSTITUTION: A movable contact plate 12 urged with a spring 11 is supported to a place in the peripheral part of a case 1a blown by pressure air from a cooling fan 10, and a fixed contact plate 13 is supported to a place at a face-to-face position to said movable contact plate. They constitutes a normally closed switch 14. The head 15 of a cylinder 6 is equipped with a solenoid mechanism 18 for open-close operating a suction valve 5. When a motor 2 is stopped, the switch 14 is closed and the suction valve 5 is opened by a solenoid 16. If the motor 2 is started with a compressor in a normally operating state, the switch 14 is opened by blowing air pressure from the cooling fan 10 not to operate the solenoid 16, then its spindle 17 is separated from the suction valve 5.