Abstract: The present invention is a pretrip routine for testing a refrigeration system comprising a series of tests for testing aspects of mechanical operation of various individual components of the refrigeration system. In a preferred embodiment, a control unit executes the method of the invention by first testing mechanical operation of a refrigeration system compressor, then tests for leaks in high-to-low-side valves of a refrigeration system, before testing for leaks in a discharge test valve. A control unit may also test the opening/closing operation of various refrigeration system valves before, intermediate or subsequent to executing the above tests. The pretrip routine of the invention validates operation of a refrigeration system as a whole by testing the mechanical operation of individual system component, and, in testing the operation of those various system components, readily isolates the source of a particular problem within a particular component of a refrigeration system.

Abstract: A method for the automated detection of leaks between the high and low-pressure sides of a refrigeration system is provided. A large pressure difference is created between the high pressure side and low-pressure side. By measuring and comparing system pressures at different times, the operational condition of valves which connect the high pressure side to the low-pressure side is accurately determined. By accurately determining that these valves are operating correctly, and in particular that no leaks exist in the valves, reports of false failures are prevented, while the reduction in the refrigeration system's capacity to heat or cool is prevented.

Abstract: A method is provided for controlling a pressure in a refrigeration system which maintains a pressure within a refrigeration system below a predetermined upper limit, may optionally maintain the pressure above a predetermined lower limit. The pressure being controlled can be a discharge pressure, a suction pressure or the difference therebetween.

Abstract: A method is provided for determining whether leaks are present in a discharge check valve of a refrigeration system. The method includes steps of establishing a pressure difference between a high pressure side and a low pressure side of the refrigeration system, temporarily stopping compression of a refrigerant, allowing the refrigerant to flow to the low-pressure sides, and then determining the discharge pressure changes with time.