Patent ID: 7386985

Claim:
A method of determining the adequacy of refrigerant charge in an air conditioning system having a refrigerant flowing serially through a compressor, a condenser, an expansion device and an evaporator, comprising the steps of: sensing the temperature of the refrigerant at an intermediate point in said condenser to obtain a first temperature; sensing the temperature of the refrigerant at a discharge end of said condenser to obtain a second temperature; calculating the difference between said first and second temperatures to obtain a coil temperature difference; comparing said coil temperature difference with predetermined values to determine the refrigerant charge adequacy of the system sensing the temperature at the discharge of the compressor to obtain a third temperature; and using said third temperature to validate the determination of charge adequacy by calculating a first residual value R 1 using said first, second and third temperatures; and on the basis of the residual value R 1 determining whether the refrigerant charge is at neither a significantly high nor a significantly low level and therefore useful for the two-temperature method of determining charge adequacy, or whether the refrigerant charge level is significantly high or whether the level of refrigerant charge is significantly low.