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6.12.2 Valve Replacement
a. Removing the Expansion Valve
NOTES
1. The TXV's are hermetic valves and do not
have adjustable superheat.
2. All connections on the evaporator TXV are
bi--metallic, copper on the inside and
stainless on the outside. When brazing,
bi--metallic connections heat up very
quickly.
6
5
1.
Evaporator Expansion Valve
2.
Non-adjustable Superheat Stem
3.
Equalizer Connection
4.
Inlet Connection
5.
Outlet Connection
6.
Expansion Valve Bulb
Figure 6-14 Evaporator Expansion Valve
INLET
Figure 6-15 Quench & Economizer Expansion
Valves
1. Pump down the unit per paragraph 6.3.2. Evacuate if
unit is not equipped with service valves. Refer to
paragraph 6.4.4.
2. Remove cushion clamps located on the inlet and out-
let lines.
3. Unbraze the equalizer connection (if applicable), the
outlet connection and then the inlet connection.
4. Remove insulation (Presstite) from expansion valve
bulb.
5. Unstrap the bulb, located below the center of the
suction line (4 o'clock position), and remove the
valve.
b. Installing the Expansion Valve
T-320
1
2
3
4
OUTLET
6-14
1. Clean the suction line with sandpaper before instal-
ling bulb to ensure proper heat transfer. Apply ther-
mal grease to the indentation in the suction line.
2. Strap the thermal bulb to the suction line, making
sure bulb is placed firmly into the suction line. See
Figure 6-12 for bulb placement.
3. Insulate the thermal bulb.
4. The economizer and quench valves should be
wrapped in a soaked cloth for brazing. For the evap-
orator valve, see Figure 6-13. Braze inlet connection
to inlet line
5. Braze outlet connection to outlet line.
6. Reinstall the cushion clamps on inlet and outlet lines.
7. If applicable, braze the equalizer connection to the
equalizer line.
8. Check superheat (refer to step 6.12.1).
6.13 EVAPORATOR COIL AND HEATER
ASSEMBLY
The evaporator section, including the coil, should be
cleaned regularly. The preferred cleaning fluid is fresh
water or steam. Another recommended cleaner is
Oakite 202 or similar, following manufacturer's
instructions.
The two drain pan hoses are routed behind the
condenser fan motor and compressor. The drain pan
line(s) must be open to ensure adequate drainage.
6.13.1 Evaporator Coil Replacement
a. Pump unit down. (Refer to paragraph 6.3.2.) Evacua-
te if unit is not equipped with service valves. Refer to
paragraph 6.4.3.
b. With power OFF and power plug removed, remove
the screws securing the panel covering the evapora-
tor section (upper panel).
c. Disconnect the defrost heater wiring.
d. Disconnect the defrost temperature sensor (see Fig-
ure Figure 2-2 from the coil. .
e. Remove middle coil support.
f. Remove the mounting hardware from the coil.
g. Unsolder the two coil connections, one at the distribu-
tor and the other at the coil header.
h. After defective coil is removed from unit, remove
defrost heaters and install on replacement coil.
i. Install coil assembly by reversing above steps.
j. Leak check connections. Evacuate and add refriger-
ant charge.
6.13.2 Evaporator Heater Replacement
a.Before servicing unit, make sure the unit circuit break-
ers (CB-1 & CB-2) and the start-stop switch (ST) are
in the OFF position, and that the power plug and cable
are disconnected.
b. Remove the lower access panel (Figure 2-1) by
removing the T.I.R. locking device lockwire and
mounting screws.
c. Determine which heater(s) need replacing by check-
ing resistance on each heater. Refer to paragraph 2.3
for heater resistance values
d. Remove hold-down clamp securing heaters to coil.
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