What are the steps for recharging refrigerant in a car's air conditioning system?

[MacAlan]

The steps for recharging refrigerant in a car's air conditioning system are: 1. Prepare intact and qualified refrigerant and charging tools; 2. Connect the car's air conditioning system to the charging tool with an adapter; 3. Inject liquid refrigerant from the high-pressure side. Methods to determine whether a car's air conditioning system needs refrigerant recharge are: 1. If there are continuous bubbles in the sight glass of the pipeline when the air conditioning is running, it indicates low refrigerant level; 2. If there are no bubbles whether the air conditioning is running or stopped, it indicates excessive refrigerant; 3. If there are no bubbles when the air conditioning is running but briefly appear when it stops, it indicates normal refrigerant level; 4. Open the hood and check if there are oil stains at the air conditioning system joints, as oil stains indicate a refrigerant deficiency.