What are the main methods for adding refrigeration oil?

[DeFrancisco]

The main methods for adding refrigeration oil are: Direct addition: Add directly from the compressor. First, perform an oil return operation. Run the compressor at idle speed with the control system set to the coldest temperature and highest fan speed for 20 to 30 minutes to allow the oil to return to the compressor. Then, turn off the engine, release the refrigerant, remove the compressor from the vehicle, drain the old oil, and directly add or replenish new oil. Another method is high-pressure side addition: Add from the high-pressure side. Evacuate to 98 kPa, close the high-pressure side manual valve, and close the service valve on the compressor. Remove the high-pressure side hose from the gauge head and insert it into the refrigeration oil. Open the service valve, and the refrigeration oil will be drawn into the system. Immediately close the service valve when the oil is almost fully drawn to avoid sucking in air. Then, reattach the high-pressure hose to the gauge head, open the high-pressure side manual valve, continue evacuating, and then add refrigerant. During oil addition, neither the engine nor the vacuum pump should be operating.