A method of controlling fluid flow through a heating, ventilating, air conditioning, and refrigeration (HVAC-R) system includes measuring temperature and pressure at an outlet of an evaporator of the HVAC-R system, wherein the evaporator is in fluid communication with a compressor, a condenser, an expansion device between the evaporator and the condenser, and a flow control valve between the compressor and the condenser, and measuring a sub-cooling temperature at an outlet of the condenser. The measured evaporator temperature and pressure data is sent to a first superheat processor, and the measured sub-cooling temperature data is send to a second superheat processor. A control signal to the expansion device from the first superheat processor and a control signal to the flow control valve from the second superheat processor are then simultaneously sent.