Lennox MMA018SM4 Service Manual page 67

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14.2.5. Adding Refrigerant if Pipe Length Exceeds Charge Less Pipe Length
Connect the charge hose to the charging cylinder and open the liquid side and suction side valves. With the charge
hose you disconnected from the vacuum pump, connect it to the valve at the bottom of the cylinder.
If the refrigerant is R410A, place the cylinder bottom-up to ensure liquid charging is possible.
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 (be careful of the liquid
refrigerant).
Place the charging cylinder onto the electronic scale and record the weight.
Turn on the air conditioner in cooling mode.
Open the valves (Low side) on the charge set. Charge the system with liquid refrigerant.
When the electronic scale displays the proper weight (refer to the table), disconnect the charge hose from the
suction side valve's service port immediately and turn off the air conditioner before disconnecting the hose.
Mount the valve stem caps and the service port. Use a torque wrench to tighten the service port cap to a torque of
18N.m (13.27 ft·lbs).
Be sure to check for gas leaks.
14.2.6. Add Refrigerant after Long-Term System Operation
Connect the charge hose to the suction side service port and open the liquid side and suction side valves.
Connect the charge hose to the valve at the bottom of the cylinder. If the refrigerant is R410A, place 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).
Place the charging cylinder onto the electronic scale and record the weight.
Turn on the air conditioner in cooling mode.
Open the valves (Low side)on the charge set and charge the system with liquid refrigerant.
When the electronic scale displays the proper weight (refer to the gauge and the pressure of the low side),
disconnect the charge hose from the suction side valve's service port immediately and turn off the air conditioner
before disconnecting the hose.
Mount 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).
Be sure to check for gas leaks.
14.2.7. Servicing Indoor Unit Refrigeration Circuit
14.2.7.1 Collecting Refrigerant into Outdoor Unit
• Confirm that both the liquid side and suction side valves are set to the opened position
• Remove the valve stem caps and confirm that the valve stems are in the opened position.
• Be sure to use a hexagonal wrench to operate the valve stems.
• Connect the suction side charge hose to the gas valve service port.
• Air purging of the charge hose - Open the suction side of the manifold valve slightly to purge air from the charge
hose for 5 seconds and then close it quickly.
• Set the liquid side valve to the close position. 5). Operate the air conditioner at the cooling cycle and stop it when
the gauge indicates 0.1MPa (14 psi).
67

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Mma024sm4Mma036s4Mma048s4Mma060s4

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