Pumping Down The Low Side; Pumping Down The Compressor; Adjusting The Charge Level - Carrier VECTOR 6500 Operation & Service Manual

the cylinder. The amount of refrigerant going into the
cylinder can be monitored by watching the weight of
the cylinder.
5. Shut down the unit when the suction pressure drops
to 2 psig (0.2 bar). There should be very little refriger-
ant remaining in the system at this point.
6. Place the unit in Service Mode (Refer to Section
5.2.3). Ensure that the microprocessor Mes-
sageCenter displays "RECOVER/LEAK CHK/EVAC
MODE" during the refrigerant removal procedures. If
the microprocessor 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 re-
frigerant recovery cylinder (or continue to use the
same cylinder used in step 3) as shown in
Figure 8−18 and remove any remaining refrigerant
from the system.
8. Refer to instructions provided by the manufacturer of
the refrigerant recovery unit.
9. After making necessary repairs, leak check, evacu-
ate 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, evaporator outlet
pressure transducer, 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 Figure 8−18.
2. Start the unit.
3. Frontseat the liquid line service valve.
4. Shut down the unit when the suction pressure drops
to 2 psig (0.2 bar). There should be very little refriger-
ant 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 may not be closed
properly. In this case, the low side cannot be
pumped down and the entire refrigerant charge
must be removed from the system. (Refer to pre-
ceding step c.)
6. Ensure the unit will not start automatically by dis-
abling any two way communication and placing the
Main Power switch in the OFF position. Disconnect
the high voltage source and lockout/tagout the re-
ceptacle.
7. Frontseat (close by turning clockwise) the discharge
service valve and the refrigerant will be trapped be-
tween the compressor discharge service valve and
the liquid line service valve.
8. Before opening up any part of the low side of the sys-
tem, a slight positive pressure should be indicated on
the pressure gauge. If the pressure is below 0 psig/
62-11389
bar slowly open the liquid line service valve slightly
and then frontseat the valve again. Repeat as neces-
sary in order to raise the pressure above 0.
9. Connect a refrigerant recovery device and a clean re-
frigerant recovery cylinder to the suction and dis-
charge service valves and remove any remaining re-
frigerant 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 system.
(Refer to Sections 8.6.3 and 8.6.4.)
e. Pumping Down The Compressor
The compressor or any of the components attached to it
(unloaders, high pressure switch, discharge and suction
pressure transducers, discharge temperature sensor,
compressor heads and oil, etc.) may be serviced or
replaced by pumping the compressor down, and
isolating the compressor from the rest of the system.
1 Install a manifold gauge set to allow reading of suction
and discharge pressure. See Figure 8−18.
2 If the compressor is operational, start the unit and
slowly frontseat the suction service valve. Shut down
the unit when the suction pressure drops to 2 psig (0.2
bar). Ensure the unit will not start automatically by dis-
abling any two way communication and placing the
Main Power switch in the OFF position. Disconnect
the high voltage source and lockout/tagout the re-
ceptacle. Frontseat the discharge service valve to
isolate compressor. There should be very little refri-
gerant remaining in the compressor at this point.
3 If the compressor is not operational, ensure the unit
will not start automatically by disabling any two way
communication and placing the Main Power switch in
the OFF position. Disconnect the high voltage source
and lockout/tagout the receptacle. and then frontseat
both the discharge and suction service valve to isolate
the compressor.
4 Connect a refrigerant recovery device and a clean re-
frigerant recovery cylinder to the suction and dis-
charge service valves and remove any remaining re-
frigerant from the compressor. DO NOT bring the
compressor pressure below 0 psig/bar.
5. After making necessary repairs, leak check and
evacuate the compressor. (Refer to Sections 8.6.3
and 8.6.4.)
f. Adjusting The Charge Level
Adjustment of the charge level may be required when
there has been a leak or the system was not correctly
charged during a previous service.
1 Check charge level by performing the procedures of
the preceding step a.
2 If charge removal is required: connect a clean evacu-
ated refrigerant recovery cylinder to the liquid line ser-
vice valve. Open liquid valve on cylinder. Midseat li-
quid line service valve and monitor the liquid
refrigerant flow into the cylinder. If the unit is operat-
ing, close the cylinder valve and backseat the liquid
line service valve when the ball in the upper sight
glass drops to the bottom of the glass. It the unit is not
operating, when approximately 5 lbs. (2.3 kg) have
been removed close the cylinder valve and backseat
the liquid line service valve. Proceed to step 7
8−16