TM 9-4120-357-14
CAUTION
Maintain a 1-2 CFM (0.5 - 1M3) flow of dry nitrogen through the refrigeration system to
prevent oxidation and scaling when brazing or debrazing components.
(7) Debraze the expansion valve body from the liquid line coming from the sight-glass liquid indicator.
(8) Working inside the evaporator intake chamber insert a sheet of scrap metal between the casing insulation and the
brazed joint of the suction line to act as a heat shield. With an assistant pulling up on the evaporator coil (2, Figure 4-7)
debraze the joint.
d. Disassembly. Debraze and remove the expansion valve body (14) from the coil (2) and distributor assembly (3)
. Debraze and remove the suction tube extension (4) from the header.
(1) Assemble and braze and header extension tube (4) to the coil (2) .
(2) Assemble the expansion valve body (14) , liquid line connector and distributor assembly (3) . Braze joints.
(3) Install coil assembly into air conditioner, and secure with six screws and washers at each end of the coil.
NOTE
It may be convenient to disconnect the equalizer line from the expansion valve power as-
sembly to facilitate assembly of the valve.
(4) Install the cage assembly (7, Figure 5-4) in the expansion valve power assembly (1) . Make sure that the lugs on
the cage assembly fit into the recesses in the body (9) . Assemble the valve body (9) and the power assembly (1) , us-
ing new gaskets (8) and (6) . Secure with two capscrews. Reconnect Equalizer line to power assembly, if removed.
CAUTION
Maintain a 1-2 CFM (0.5-1 M3) flow of dry nitrogen through the refrigeration system to
prevent oxidation and scaling when brazing or debrazing components.
(5) Use a sheet metal heat shield between the joint and the insulation in the casing. Braze the joint from the header
to the suction line (4) inside the evaporator intake chamber.
(6) Install the heater assembly (Figure 4-14) behind the evaporator coil. Secure with two screws through each return
air chamber into the heater support bracket (8) . Connect wiring harness plug, P7, to receptacle in wall of right-hand
return air chamber.
f. 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 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 flow of 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.
5-61
