A refrigeration system (10) for cooling or heating an area includes a condenser (20) for removing heat from the system to an external environment, an evaporator (22) for receiving heat from the area to be cooled or delivering heat to the area to be heated, and a compressor (12) for raising the pressure and the temperature of a refrigerant. Prior to placing the system in a cooling or heating/defrost mode, it is desirable to run a pretrip routine to determine the operational condition of the refrigeration system. In the present invention, a pretrip device determines a refrigeration system parameter, and from this parameter selects one of at least two possible pretrip routine variations. Finally, the pretrip device executes the selected pretrip routine in order to determine the operational condition of a refrigeration system.