A method of operating a refrigerant service system to charge an air conditioning circuit includes pre-charging a predetermined pre-charge quantity of refrigerant into the air conditioning circuit, determining an average temperature in the air conditioning circuit based upon a pressure in the air conditioning circuit after pre-charging the air conditioning circuit, determining a charge compensation value based upon the determined average temperature in the air conditioning circuit, and charging the air conditioning circuit with a quantity of refrigerant based upon the charge compensation value.