4-462-10630
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1 Refrigerant Recovery Unit
2 Refrigerant Cylinder
3 Evacuation Manifold
4Valve
5 Vacuum Pump
6 Electronic Vacuum Gauge
Figure 4-2. Vacuum Pump Connection
g. Remove refrigerant usinga refrigerant recovery sys-
tem.
h. Repeat steps e. to g.
i. If required, remove the copper tubing and install a
new filter--drier . Evacuate unit to 500 microns. Close
offvacuum pumpvalveandstoppump.W aitfivemin-
utes to see if vacuum holds. This checks for residual
moisture and/or leaks.
j. With a vacuum still in the unit, the refrigerant charge
maybedrawnintothesystem from a refrigerant con-
tainer on weight scales. Continue to paragraph
4.10.2.
4.9.4Evacuation and Dehydration -- Partial Sys-
tem.
a. If the refrigerant charge has been removed from the
standby compressor for service, evacuate only the
compressor by connecting the evacuation set--up at
the compressor service valves. Follow evacuation
procedures of the preceding paragraph except leave
compressor service valves frontseated until evacua-
tion is completed.
b. If refrigerant charge has been removed from the low
side only, evacuate the low side by connecting the
evacuation set--up at the standby compressor suc-
tion service valve and liquid service valve except
leave the service valves frontseated until evacuation
is completed.
c. Once evacuation has been completed and the pump
hasbeenisolated,fullybackseattheservicevalvesto
isolate the service connections and then continue
with checking and, if required, adding refrigerant in
accordance with normal procedures
4.10 CHARGING THE REFRIGERATION SYSTEM
4.10.1 Checking The Refrigerant Charge
Start unit in cooling mode. Run approximately ten
minutes. Partially block off air flow to condenser coil
increase the area blocked until compressor discharge
pressure is raised to approximately 325 psi (22 bars).
Thechargeiscorrect if therearenobubblesattheliquid
line sight glass.
4.10.2 Installing A Complete Charge
a. Evacuate the refrigeration circuit and leave in a deep
vacuum (refer to paragraph 4.9).
b. Place a refrigerant 404A cylinder on scale and con-
nect charging line from cylinder to manifold. Purge
charginglineat outlet valve. Purgecharging lineatin-
let manifold.
c. Note weight of refrigerant cylinder.
d. Open liquid valve on refrigerant cylinder . Open liquid
line service valve half way and allow the liquid refrig-
erant toflow intotheunit untilthe correct weight of re-
frigerant has been added as indicated by scales.
(Correct charge will be found in paragraph 1.2).
NOTE
It may be necessary to finish charging the unit
using the partial charge method, due to pres-
sureriseinthehighsideofthesystem.(Referto
paragraph 4.10.3)
e. When refrigerant cylinder weight (scale) indicates
that the correct charge has been added, close the
manifold valves.
f. Open the receiver valve back seat and check charge
in accordance with paragraph 4.10.1.
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