Fisher FSAI-SU-90AE2 Service Manual page 22

Be sure to check for gas leakage.
2. Air purging by the refrigerant
Procedure:
1). Confirm that both the 2-way and 3-way valves are set to the closed position.
2). Connect the charge set and a charging cylinder to the service port of the 3-way valve
Leave the valve on the charging cylinder closed.
3). Air purging.
Open the valves on the charging cylinder and the charge set. Purge the air by loosening the flare nut on
the 2-way valve approximately 45' for 3 seconds then closing it for 1 minute; repeat 3 times.
After purging the air, use a torque wrench to tighten the flare nut on the 2-way valve.
4). Check the gas leakage
Check the flare connections for gas leakage.
5). Discharge the refrigerant.
Close the valve on the charging cylinder and discharge the refrigerant by loosening the flare nut on the
2-way valve approximately 45' until the gauge indicates 0.3 to 0.5 Mpa.
6). Disconnect the charge set and the charging cylinder, and set the 2-way and 3-way valves to the open
position
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