Verify the system uses a refrigerant type you are certified to handle
Turn off power to the HVAC or refrigeration system
Inspect for leaks and repair them before adding refrigerant
Connect a manifold gauge set to the appropriate service ports
Purge air from the hoses
Check the system’s required refrigerant charge from the manufacturer label
Place the refrigerant cylinder on a scale if charging by weight
Open the refrigerant cylinder valve
Start the system and let it stabilize
Add refrigerant slowly through the correct side of the system
Monitor pressures, temperatures, and superheat or subcooling as required
Stop charging when the specified charge is reached
Close the cylinder valve and manifold valves
Disconnect the gauges and replace service port caps
Check system operation and verify proper performance
Confirm there are no leaks after charging