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8–22
c. Removing Charge
To remove the refrigerant charge, proceed as follows:
1. If the system is in operating condition, it will be
quicker to remove the charge by continuing with
step 2. If the system is not in operating condi-
tion, skip steps 2 through 5 and continue with
step 6.
2. Install a manifold gauge set to allow reading of
suction and discharge pressure. See
CAUTION
!
Only a refrigerant cylinder that has previ-
ously been used with R404A should be
connected to this refrigeration unit.
3. Connect a clean, evacuated refrigerant cylinder
to the liquid line service valve connection. Place
the cylinder on a weight scale so the refrigerant
going into the cylinder can be monitored.
4. Start the unit and run in high speed cool. Cover
the condenser to raise the discharge pressure to
as high as 375 psig (25.5 bar). Do not let the dis-
charge pressure exceed 400 psig (27.2 bar).
Open the refrigerant cylinder valve, and allow the
refrigerant to flow into the cylinder. The amount of
refrigerant going into the cylinder can be moni-
tored by watching the weight of the cylinder.
5. Shutdown the unit when the suction pressure
drops to 2 psig (0.2 bar). There should be very
little refrigerant remaining in the system at this
point.
6. Place the unit in Service Mode (Refer to
). Ensure that the operator message
panel displays “RECOVER/LEAK CHK/EVAC
MODE” during the refrigerant removal proce-
dures. If the control system switches to charge
mode during the process, switch it back to the
“RECOVER/LEAK CHK/EVAC MODE”.
7. Connect a refrigerant recovery device and a
clean refrigerant recovery cylinder (or continue
to use the same cylinder used in step 3) as
shown in
and remove any remain-
ing refrigerant from the system.
8. Refer to instructions provided by the manufac-
turer of the refrigerant recovery unit.
9. After making necessary repairs, leak check,
evacuate and recharge the system.
d. Pumping Down The Low Side
Components on the low side of the refrigeration system
(the filter drier, EVXV, evaporator coil, CSMV, heat
exchanger, suction line etc.) may be serviced or
replaced without having to completely remove the
refrigerant charge from the system by pumping down
the low side, and temporarily storing the refrigerant in
the condenser and receiver.
1. Install a manifold gauge set to allow reading of
suction and discharge pressure. See
2. Start the unit.
3. Frontseat the liquid line service valve.
4. Shutdown the unit when the suction pressure
drops to 2 psig (0.2 bar). There should be very
little refrigerant remaining in the low side of the
system at this point.
5. Monitor the gauges. The suction pressure
should not rise rapidly. If the suction pressure
continues to rise, the liquid line service valve or
bypass check valve may not be closing properly.
In this case, the low side cannot be pumped
down and the entire refrigerant charge must be
removed from the system. (Refer to preceding
step c.)
6. Ensure the unit will not start automatically by dis-
abling any two way communication and placing
the STOP/RUN-OFF switch in the OFF position.
7. Frontseat (close by turning clockwise) the dis-
charge service valve and the refrigerant will be
trapped between the compressor discharge ser-
vice valve and the liquid line service valve.
8. Before opening up any part of the low side of the
system, a slight positive pressure should be
indicated on the pressure gauge. If the pressure
is below 0 psig/ bar slowly open the liquid line
service valve slightly and then frontseat the
valve again. Repeat as necessary in order to
raise the pressure above zero.
9. Connect a refrigerant recovery device and a
clean refrigerant recovery cylinder to the suction
and discharge service valves and remove any
remaining refrigerant from the low side. DO
NOT bring the low side pressure below 0 psig/
bar.
10. After making necessary repairs, leak check and
evacuate the low side of the refrigeration sys-
tem. (Refer to
and
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