Based on a result of detection taken by the high-low pressure difference detection means (93, 97) for detecting a difference between a high and a low pressure of a refrigeration cycle, an estimate of whether there is leakage of refrigerant in an expansion valve (52) is made. Based on the result detected by the high-low pressure difference detection means (93, 97), a control means (81) sets a reference temperature (T3) to a value corresponding to the degree of refrigerant leakage in the expansion valve (52).