A system is provided and may include a compressor having a motor and a refrigeration circuit including an evaporator and a condenser fluidly coupled to the compressor. The system may further include a first sensor producing a signal indicative of one of current and power drawn by the motor, a second sensor producing a signal indicative of a saturated condensing temperature, and a third sensor producing a signal indicative of a liquid-line temperature. Processing circuitry may processes the current or power signal to determine a derived condenser temperature and may compare the derived condenser temperature to the saturated condensing temperature received from the second sensor to determine a subcooling associated with a refrigerant charge level of the refrigeration circuit.