This paper presents the development of a computer program for component matching of a mixed vapor compression system. A mixed system is one in which the components are assembled from various manufacturers. The component matching program is developed to predict the performance of the entire mixed system when the characteristics of the individual components are known. The characteristic equation of each component is derived from TRANE performance charts and data. The balancing point of the matched system is obtained according to the required input variables. Six TRANE reciprocating compressors, of 1540 T.R., were mix-matched with five different capacities of water cooled condensers. Performance charts of the six optimum condensing units are obtained, along with over and under sized system matching characteristics. This allows instant selection of different compressor sizes vs. water cooled condensers, which is not readily available from the manufacturer. The proposed optimum condensing units are thereafter coupled with five various capacities of shell and tube evaporators. The overall system characteristic curve was established for various entering chilled water temperatures to each proposed combination. Tables of optimum, over and under sized possible combinations were obtained.