According to different pressures of different refrigerants, look at the pointer reading of the pressure gauge. When the air conditioner is filled with fluorine, a special composite pressure gauge is used, and the low pressure hose connector is connected to the low pressure maintenance valve of the air conditioner outdoor unit, the yellow hose connector is connected with the refrigerant tank, the refrigerant tank valve is opened, and the low pressure valve is opened. Fluorine action. If it is R22 refrigerant, after filling for a period of time (about 10 seconds), close the low pressure valve and read the pointer reading value of the low pressure meter. Under the operating state of the compressor, the reading value is about 0.5 M Pa. If it does not reach this finger, it will continue to open. The low pressure valve is filled and the above operation is repeated until the low pressure gauge reading reaches 0.5 M Pa.