In this paper the temperature of vaporization caused by the sur- face area of defrosting heat exchange, the wind pressure difference at inlet and outlet, andthe electric current of motor as well as its rotating speed during the air cooler runningwere experimentally and theoretically studied. Besides, optimal control of the initialdefrosting point in the air cooler and the technology for energy saving during defrosting were elucidated. The experimental results showed that the proper selection ofcontrolled defrost method would significantly improve the technology of defrosting inthe air cooler, expand the extent of automation in the refrigeration system and realizethe energy saving during operation.