Abstract Refrigerant migration during start-up and shut-down cycles can affect energy losses. Two reciprocating compressor refrigeration systems were studied: (1) a conventional cycle with refrigerant migration through the capillary tube after compressor shut-down and (2) a system in which a magnetic cut-off valve was closed on compressor shut-down. It was found that by preventing the refrigerant from migrating during shut-down, energy losses during start-up could be reduced, resulting in a 4% decrease in motor power input at this time. A computer program has been developed to calculate energy losses due to refrigerant migration.