The ExactCharge Calculator contains a diagnostic assistant screen to aid service technicians in determining refrigerant state malfunctions occurring in a system. This text screen includes diagnostics for fixed metering devices as well as txv metering devices. It is able to refer the technician to a likely component failure or condition that could be effecting the systems operation. By referencing text with actual readouts outputted from the calculator the service technician is quickly able to determine refrigerant state malfunctions occurring in the system. Readouts include diagnostics for blocked coils, liquid restrictions, hot gas bypasses, and others.