Lennox MMA018SM4 Service Manual page 68

• Set the suction side valve to the closed position immediately
• Do this quickly so that the gauge ends up indicating 0.3 to 0.5Mpa (43 - 72 psi).
• Disconnect the charge set, and tighten the liquid side and suction side valve's stem nuts.
• Use a torque wrench to tighten the suction side valves service port cap to a torque of 18N.m.
• Be sure to check for gas leakage.
14.2.7.2 Air Purging with Vacuum Pump
• Completely tighten the flare nuts of the indoor and outdoor units, confirm that both the liquid side and suction side
valves are set to the closed position.
• Connect the suction side charge hose to the gas valve service port.
• Connect the high side charge hose to the vacuum pump.
• Fully open the suction side of the manifold valve.
• Operate the vacuum pump to evacuate.
• Make evacuation for 30 minutes and check whether the compound meter indicates - 0.1Mpa (500 microns). If
the meter does not indicate - 0.1Mpa (500 microbars) after pumping 30 minutes, it should be pumped 20 minutes
more. If the pressure can't achieve -0.1Mpa (500 microbars) after pumping 50 minutes, please check if there are
some leakage points.
• Fully close the suction side of the manifold valve and stop the operation of the vacuum pump. Confirm that the
gauge needle does not move (approximately 5 minutes after turning off the vacuum pump).
• Turn the flare nut of the suction side valves about 45° counterclockwise for 6 or 7 seconds after the gas coming
out, then tighten the flare nut again. Make sure the pressure display in the pressure indicator is a little higher than
the atmosphere pressure. Then remove the charge hose from the suction side valve.
• Fully open the liquid side valve and suction side valve and securely tighten the cap of the suction side.
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