What are the steps for adding refrigerant to a car?

[VonAlice]

The steps for adding refrigerant to a car are: 1. After the system is vacuumed, close the high and low pressure manual valves on the manifold pressure gauge; 2. Connect one end of the middle hose to the refrigerant tank injection valve fitting, open the refrigerant tank valve, then loosen the nut at one end of the manifold pressure gauge hose to let gas escape for a few minutes before tightening the nut; 3. Open the high-pressure side manual valve fully and invert the refrigerant tank; 4. Inject the specified amount of liquid refrigerant from the high-pressure side, close the refrigerant tank injection valve and the high-pressure manual valve on the manifold pressure gauge, remove the gauge. When adding refrigerant to the system from the high-pressure side, the engine must be off (compressor stopped), and do not open the low-pressure manual valve on the manifold pressure gauge to prevent hydraulic shock.