The BMW 520 air conditioning system generally requires about 650 grams of refrigerant, which is approximately two and a half bottles. The recommended filling amount is usually indicated on the engine hood. Alternatively, you can also check the pressure on the air conditioning gauge. Prerequisites for adding car air conditioning refrigerant: Before adding refrigerant, it is essential to assume that the air conditioning system has no leaks. Preparations for adding car air conditioning refrigerant: Before adding refrigerant, prepare a vacuum pump, manifold gauge, refrigerant, electronic scale, etc. System vacuuming: Connect the vacuum pump and the charging port on the air conditioning pipeline using the manifold gauge to vacuum the system. Observe the scale on the manifold gauge. After reaching the maximum vacuum, continue vacuuming for at least half an hour. Then, close the manifold gauge hand valve, turn off the vacuum pump, and maintain the pressure for about 10 minutes. Observing the scale on the manifold gauge: Check the scale on the manifold gauge. If the system vacuum remains stable, disconnect the manifold gauge tube from the vacuum pump. Connect one end to the low-pressure pipe charging port and the other end to the refrigerant cylinder. Before opening the manifold gauge hand valve, first open the refrigerant cylinder, loosen the pipeline joint to purge air from the pipeline using the refrigerant, and then tighten it. Refrigerant filling amount: If the specified refrigerant filling amount for the car's air conditioning system is known, use an electronic scale to measure the exact amount, controlling the filling quantity by weighing the cylinder. If the exact filling amount is unknown, first loosen the manifold gauge hand valve without starting the air conditioning and add as much refrigerant as possible. Then, start the engine, turn on the air conditioning, and gradually increase the engine speed to 1200~1500 rpm. Observe the sight glass on the receiver-drier. Initially, there will be bubbling, which will gradually decrease. When the bubbles disappear, close the manifold gauge hand valve. Closing the refrigerant cylinder: Close the refrigerant cylinder, disconnect the manifold gauge tube from the air conditioning low-pressure pipe, and the car air conditioning refrigerant filling process is complete.
