How to Do a Triple Evacuate on an R22 Central AC System

Attach the mercury U-tube manometer to the evaporator's service port. Ensure that it is installed vertically so the readings will be accurate. Connect the AC gauges and vacuum pump to the compressor's suction valve. Open the manifold's suction valves and activate the pump. Monitor the manometer and stop the vacuum pump once the manometer indicates that the vacuum has reached 1 mm Hg.

Attach the R-22 refrigerant to the system through the gauge manifold. Open the valve on the refrigerant tank and allow a small amount of R-22 to enter the system. Close the R-22 tank once the gauge shows the vacuum has reached 20 inches Hg. Start the vacuum pump and allow it to operate until the vacuum reaches 1 mm Hg.

Open the R-22 tank and allow the refrigerant to enter the system again until the vacuum reaches 20 inches Hg. Close the R-22 tank and start the vacuum pump. Allow the pump to run for at least twenty minutes. Monitor the manometer and once the mercury columns are equal, turn off the pump. Disconnect the manometer.

Charge the system with refrigerant. Disconnect refrigerant tank and AC gauge manifold. Double-check the system ports to ensure that the service port seals have been replaced.