TM 9-4120-357-14
(3) Loosen the setscrew in the end of core end fitting (14, Figure 4-3) and remove the end fitting from the flexible
cable core. Remove two screws and washers from the hold-down clamp (16) , and move the cable out of the way. Re-
move six screws that secure the junction box mounting flange to the casing, and remove two screws (8) and washers
(9) from the lower right mounting bracket. Detach control thermostat sensing bulb and capillary tube from air condi-
tioner, and carefully coil capillary tube to prevent kinking. Remove the junction box and control panel assembly.
b. Discharging the System. Whenever a leak is detected or a refrigeration component must be replaced, you
must discharge all gas from the refrigeration system in accordance with paragraph 5--6.
c. Removal.
CAUTION
If unscrewing torque would place an undue strain on adjacent piping and fittings, use a
back-up wrench to hold the fitting steady. Unscrew and remove the pressure relief valve
(16, Figure 5-2) from the cross fitting (14) .
d. Installation. Apply teflon pipe-thread tape to threads of the pressure relief valve. Screw the pressure relief valve
(15) into the cross fitting (14) as far as possible by hand. Tighten with two wrenches: One on the fitting and one on the
valve, to prevent strain.
e. Purging the System.
CAUTION
Whenever the refrigeration system has been opened to the atmosphere, you must install
a new drier-strainer (dehydrator) before purging and recharging the system.
With the refrigeration system discharged and a hose attached to the gage port of the suction service valve, connect a
cylinder of oil-pumped dry nitrogen to the gage port of the high-pressure service valve. Open the high-pressure service
valve, and crack open the cylinder shutoff valve to establish a 1-2 CFM (0.5 --1 M3) through the system. Purge for at
least 30 minutes to expel all other gases, impurities and water vapor. Turn off both service valves before disconnecting
the nitrogen cylinder and the discharge hose.
f. Charging the System. Prepare the refrigeration system for charging by attaching a pressure gage to the high-
pressure service valve gage port, and a pressure hose and drier-strainer, loosely, to the suction service valve
gage port. Leave both valves closed. Proceed as follows:
WARNING
Avoid contact with liquid refrigerant or escaping refrigerant gas. Irreversible tissue dam-
age can result from sudden freezing. Be especially careful to protect the eyes. Avoid in-
haling high concentrations of refrigerant gas, and prevent gas coming into direct contact
with flame or hot metal surfaces; lethal phosgene gas can be formed.
(1) Connect a cylinder of refrigerant, R22, to the pressure hose. Open the cylinder shutoff valve slightly to purge the
hose of air, then tighten the hose connection to the suction service valve gage port.
(2) Open both service valves and the cylinder shutoff valve, and charge the system with refrigerant gas until the
gage on the discharge (high-pressure) service valve registers 70 PSI (5 KG/CM2) . Close the suction service valve and
the cylinder shutoff valve.
(3) Transfer the charging line to a cylinder of dry nitrogen. Open the cylinder shutoff valve and the suction service
valve, and let nitrogen flow into the refrigeration system until the discharge pressure gage reads 350 PSI (21.44
KG/CM2) . Turn off the' suction and discharge service valves and cylinder shutoff valve. Disconnect the charging line
from suction service valve.
(4) Test the refrigeration system for leaks, using an electronic leak detector, Halide torch or soap bubble method.
The electronic leak detector is preferred. Use GE type H-10 electronic leak detector or equivalent.
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