Midea MUBU-12HRFN1-M Service Manual page 47

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 0.3Mpa (43.5Psi) to 0.5
Mpa (72.5Psi).
6). Disconnect the charge set and the charging
cylinder, and set the 2-way and 3-way valves to
the open position
Be sure to use a hexagonal wrench to operate
the valve stems.
7). Mount the valve stems nuts and the service
port cap
Be sure to use a torque wrench to tighten the
service port cap to a torque 18N.m.
Be sure to check the gas leakage.
12.4.6 Re-installation while the outdoor unit
need to be repaired
1. Evacuation for the whole system
Procedure:
1). Confirm that both the 2-way and 3-way
valves are set to the opened position.
2). Connect the vacuum pump to 3-way valve's
service port.
3). Evacuation for approximately one hour.
Confirm that the compound meter indicates
-0.1Mpa (14.5Psi).
4). 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).
5). Disconnect the charge hose from the
vacuum pump.
2. Refrigerant charging
Procedure:
1). Connect the charge hose to the charging
cylinder, open the 2-way valve and the 3-way
valve
Connect the
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.
2). 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).
3) Put the charging cylinder onto the electronic
scale and record the weight.
4). Open the valves (Low side) on the charge
set and charge the system with liquid refrigerant
If the system cannot be charge with the
specified amount of refrigerant, or can be
charged with a little at a time (approximately
150g each time) , operating the air conditioner
in the cooling cycle; however, one time is not
sufficient, wait approximately 1 minute and then
repeat the procedure.
44
charge hose which you