This work deals with the study of a generalized endoreversible refrigeration cycle characterized by three heat sources with finite heat capacities. Following conventional schemes to treat the entire. system as a combined cycle of a two heat source engine driving a two heat source refrigerator (both engines with finite heat capacities), we select a particular configuration to derive a fundamental optimum formula. Therefore, the predicted optimal performance coefficient and the relationship of that with a given rate of refrigeration reveal a unified description of various endoreversible refrigerators of three heat sources previously reported in finite time thermodynamics. The numerical results show clearly the physical influence of the involved finite heat capacities, together with the thermal resistances, on the performance of the refrigeration cycle.