Having problems with a closed loop chiller supplying cooling water for a plastic molding operation. With minimal demand while equipment heats up, coolant (glycol/water) reaches set piont (45 degrees) and maintains. Once production starts, chiller no longer maintains set piont temp even though demand still seems slight. Difference in coolant temp leaving chiller and returning from process is only 4 dgrees. Have checked refrigerant charge, water flow rates, coils are clean. What should superheat range be? Is this a heat transfer problem? Any info appreciated.