Electronic Function; Abbreviations - Lennox MMA018SM4 Service Manual

14.2.8. Evacuation after Servicing the Outdoor Unit Refrigeration Circuit
14.2.8.1 Evacuation of the Complete Refrigeration Circuit, Indoor and Outdoor Unit
• Confirm that both the liquid side and suction side valves are set to the opened position.
• Connect the vacuum pump to suction side valve's service port.
• Evacuation for approximately one hour. Confirm that the compound meter indicates - 0.1Mpa (500 Microns / 29.9
in. hg).
• Close the valve (Low side) on the charge set, turn off the vacuum pump, and confirm that the gauge needle does
not move (approximately 5 minutes after turning off the vacuum pump).
• Disconnect the charge hose from the vacuum pump.
14.2.8.2 Refrigerant Charging
• Connect the charge hose to the charging cylinder, open the liquid side valve and the suction side valve.
• Connect the charge hose which you disconnected from the vacuum pump to the valve at the bottom of the
cylinder. If the refrigerant is R410A, make the cylinder bottom up to ensure liquid charge.
• Purge the air from the charge hose
• Open the valve at the bottom of the cylinder and press the check valve on the charge set to purge the air (be
careful of the liquid refrigerant).
• Put the charging cylinder onto the electronic scale and record the weight.
• Open the valves (Low side) on the charge set and charge the system with liquid refrigerant. If the system cannot
be charged with the specified amount of refrigerant, charged a little at a time (approximately 150g each time) in
the cooling cycle. Wait approximately one minute before repeating the procedure until it is properly charged.
• When the electronic scale displays the proper weight, disconnect the charge hose from the suction side valve's
service port immediately
• If the system has been charged with liquid refrigerant while operating the air conditioner, turn off the air conditioner
before disconnecting the hose.
• Mounted the valve stem caps and the service port. Use torque wrench to tighten the service port cap to a torque of
18N·m (13.27 ft·lbs).
• Always leak check after servicing the refrigerant system.
• There is one master suction valve and one master liquid valve; it save time when vacuuming and recycling
refrigerant. But refer to the previous instruction when vacuum and recycle refrigerant.

15. Electronic Function

15.1. Abbreviations

• T1: Indoor ambient temperature
• T2: Middle indoor heat exchanger coil temperature
• T2B: Indoor heat exchanger exhaust coil temperature (located on the outdoor unit)
• T3: Outdoor heat exchanger pipe temperature
• T4: Outdoor ambient temperature
• T5: Compressor discharge temperature
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