What is the correct method for adding refrigerant oil to a car's air conditioning system?

[StVivian]

The correct method for adding refrigerant oil to a car's air conditioning system: 1. Open the car's engine hood and locate the high and low pressure pipes of the air conditioning system, where the larger one is the low pressure pipe and the smaller one is the high pressure pipe; 2. Check whether the charging valve is qualified, and the use of inferior charging valves is prohibited; 3. Connect the high and low pressure pipes of the air conditioning system to the red and blue pipes on the air conditioning pressure gauge device, and connect the yellow pipe on the device to the vacuum machine for vacuuming; 4. Turn off the vacuum machine and remove the high pressure pipe; 5. Shake the bottle up and down before use to keep the contents uniform, and add an appropriate amount from the compressor service port as needed. The function of car air conditioning refrigerant oil is to lubricate, seal, cool, and regulate energy for the car's air conditioning system.