A good technician should always check the operating systems subcooling number to verify the correct range, for proper system operational efficiency.

Systems with Thermal Expansion Valve Devices must have the proper liquid amount entering the TXV, for the device to function properly. Use the condenser data plate number as the base line when charging the system. CBP products have a tolerance of ±3°F.

If the system charge is low, which results in a low sub-cooling number, then the metering device will have poor cooling effect due to not having enough liquid refrigerant entering the Thermal Expansion valve. Any refrigerant gas entering the valve will cause immediate loss of cooling.

Subcooling = the difference between the saturation temperature and the actual liquid-line temperature.

Add refrigerant to increase subcooling.

Remove refrigerant to decrease subcooling.