Abstract: A refrigerant system for a household refrigerator has its operability tested after assembly of the refrigerant system with a refrigerator cabinet. A rotary compressor of the refrigerant system is preheated, preferably by applying heat to its stator through a low AC voltage, for a predetermined period of time prior to activation of the rotary compressor. After the rotary compressor is activated, the temperature of one of the serially connected coils of the evaporator remote from the first coil is determined. If the coil temperature is within a predetermined range, this indicates the proper operability of the refrigerant system. Power consumption can be measured in conjuction with the temperature so that a significant increase or decrease in power consumption would indicate a defective refrigerant system notwithstanding the coil temperature being satisfactory.