Refrigerant System Evacuate

NOTE: Moisture must be prevented from entering the A/C oil. Moisture in the oil is very difficult to remove and will cause a reliability problem with the compressor.

If a compressor is left open to the atmosphere for an extended period of time, the refrigerant oil should be drained and replaced or install a new compressor. This will eliminate the possibility of contaminating the refrigerant system.

If refrigerant system has been open to the atmosphere, it must be evacuated before the system can be charged. Moisture and air mixed with the refrigerant will raise the compressor head pressure above acceptable operating levels. This will reduce the performance of the system and damage the compressor.

Evacuate A/C System

NOTE: When connecting the service equipment coupling to the line fitting, verify the valve of the coupling is fully closed. This will reduce the amount of effort required to make the connection.

1. Connect a suitable charging station, refrigerant recovery machine and a manifold gauge set with vacuum pump.
2. Open suction and discharge valves and start vacuum pump. The vacuum pump should run a minimum of 45 minutes to eliminate all moisture in system. When suction gauge reads -88 kPa (-26 in. Hg) vacuum or greater for 45 minutes, close all valves and turn OFF vacuum pump. If the system fails to reach specified vacuum, the system likely has a leak that must be corrected. If the refrigerant system maintains specified vacuum for at least 30 minutes, start the vacuum pump, open the suction and discharge valves. Then evacuate the system an additional 10 minutes.
3. Close all valves, turn OFF and disconnect the vacuum pump.
4. The refrigerant system is now ready to be charged with refrigerant.