How-to Diognose Low System Refrigerant Charge, Fixed Expansion Device

Low system charge can be caused by a leak or improper charge when installed.
Low charge will result in low capacity, low EER, and a hot compressor.

Systems with a low charge will operate at pressures below the factory recommended pressures. High superheat and low subcooling will be evident. The compressor will run hot with insufficient colling for the motor windings. The low suction pressure may result in sub-freezing temperatures at the evaporator causing ice to form, further inhibiting air flow.

Check for leaks.
Charge the system in accordance with manufacturers instructions to the target superheat level. Make sure when charging R-410A to add refrigerant in the liquid state only.