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Service Manual 20
Disassembly
— Replacement of the refrigeration cycle.
1. When replacing the refrigeration cycle, be sure to
Discharge the refrigerant system using a Freon
TM
recovery System.
If there is no valve to attach the recovery system,
install one (such as a WATCO A-1) before venting
the Freon
TM
. Leave the valve in place after
servicing the system.
2. After discharging the unit completely, remove the
desired component, and unbraze the pinch-off
tubes.
3. Braze service valves into the pinch-off tube ports,
leaving the valves open.
4. Braze the pinch-off tubes with Service valves.
5. Evacuate as follows.
1) Connect the vacuum pump, as illustrated figure
33A.
2) Start the vacuum pump, slowly open manifold
valves A and B with two full turns counterclockwise
and leave the valves open.
The vacuum pump is now pulling through valves
A and B up to valve C by means of the manifold
and entire system.
CAUTION: If high vacuum equip-
ment is used, just crack valves A
and B for a few minutes, then open slowly
with the two full turns counterclockwise.
This will keep oil from foaming and being
drawn into the vacuum pump.
3) Operate the vacuum pump vaccum for 20 to 30
minutes, until 600 microns of vaccum is obtained.
Close valves A and B, and observe vacuum gauge
for a few minutes. A rise in pressure would indi-
cate a possible leak or moisture remaining in the
system. With valves A and B closed, stop the vac-
uum pump.
4) Remove the hose from the vacuum pump and
place it on the charging cylinder. See figure 33B.
Open valve C.
Discharge the line at the manifold connection.
5) The system is now ready for final charging.
6. Recharge as follows :
1) Refrigeration cycle systems are charged from the
High-side. If the total charge cannot be put
in the High-side, the balance will be put in the
suction line through the access valve which you
installed as the system was opened.
2) Connect the charging cylinder as shown in figure
33B.
With valve C open, discharge the hose at the mani-
fold connection.
3) Open valve A and allow the proper charge to
enter the system. Valve B is still closed.
4) If more charge is required, the high-side will not
take it. Close valve A.
5) With the unit running, open valve B and add the
balance of the charge.
a. Do not add the liquid refrigerant to the Low-
side.
b. Watch the Low-side gauge; allow pressure to
rise to 30 lbs (0.2Mp).
c. Turn off valve B and allow pressure to drop.
d. Repeat steps b. and c. until the balance of the
charge is in the system.
6) When satisfied the unit is operating correctly,
use the pinch-off tool with the unit still running
and clamp on to the pinch-off tube. Using a tube
cutter, cut the pinch-off tube about 2 inches from
the pinch-off tool. Use sil-fos brazing rod and braze
pinch-off tube closed. Turn off the unit, allow it to
set for a while, and then test the leakage of the
pinch-off connection.
NOTICE