Patent ID: 7079967

Claim:
A method of providing diagnostics of a refrigeration system, the refrigeration system including a compressor, a condenser, an expansion device, and an evaporator connected together, the method comprising: determining the type of expansion device used in the refrigeration system; storing a plurality of HVAC system parameters that have been pre-defined for a particular refrigeration system and type of expansion device used; defining a plurality of diagnostic messages based on said particular refrigeration system; measuring at least five but not more than nine HVAC system variables; calculating various HVAC operational variables including superheat based on the measurement of said at least five HVAC system variables; comparing the calculated HVAC operational variables to said stored HVAC system parameters; and conveying at least one of said plurality of diagnostic messages to a person performing said diagnostics; wherein if it is determined during said determining step that said expansion device is a thermal expansion valve, the superheat is fixed at 20 ° F.