Arrive to calibrate a systems refrigerant charge. Previously a field supervisor came out to aid in diagnosing the system. Field supervisor determined that the system is low on refrigerant. Upon arrival connected refrigerant gauges and started reading system refrigerant charge. System appears to be overcharged, based on my readings at this time. Calibrated system and charge to factory specs. Suspect that the metering device for the refrigerant is not working properly. Calibrated system refrigerant charge to achieve a 20° temperature split. Adjusted settings on the thermostat to ensure that the system continues to maintain temperature throughout the day. System is cooling upon departure.