To prevent a refrigerator temperature from being increased by a method wherein there is provided a main control section which is operated such that an operation of an electric motor for a condenser is not carried out in reference to a temperature of a condensing temperature sensing device when a compressor is operated by a refrigerator temperature sensing device and further the operation is controlled to such a condensing temperature as one where a cooling performance is not reduced.

A main control section 11a operates a compressor 3 so as to start cooling operation when a refrigerator temperature sensing device 6 detects a value more than a predetermined temperature. Then, the main control section 11a detects a condensing temperature by a condensing temperature sensing device 12. Subsequently, when the main control section 11a detects that the condensing temperature sensing device 12 detects a value more than a predetermined temperature, an electric motor 7 for a condenser is operated. Then, the main control section 11a continues a predetermined operation until it is detected that a refrigerator temperature is detected by the refrigerator temperature sensing device 6 as one less than a predetermined temperature. With such an arrangement as above, it is possible to prevent a condensing temperature from being decreased, refrigerant from being accumulated in a condensing pipe due to liquefied state of the refrigerant, perform a normal circulation of the refrigerant and further prevent the refrigerator temperature from being increased.