In the movement of freezer, the inspiratory side of compressor of its refrigeration series calls low-pressure side, its pressure pressure of air of summary prep above. The exhaust side of compressor calls high-pressured side, pressure is as high as 117.7 handkerchief (square of 12 kilogram ／ centimeter) the left and right sides. Two side press difference very big, stop system of the two side after machine to still maintain this to press difference. If be started instantly, compressor piston pressure, the electric machinery moment of force that start is insuperable so tall press difference, make electric machinery cannot be started, be in locked-rotor condition, electric current of electric machinery winding leap, temperature rises, if time is too long, electric machinery of very possible burn down. Accordingly, requirement freezer stops machine hind to want to wait 4 - start all right again after 5 minutes.