6-15
T--317
6.14.2 Hermetic Valve Replacement
a. Removing the Expansion Valve
NOTES
1. The TXV is a hermetic valve and does not
have adjustable superheat.
2. All connections on the hermetic TXV are
bi--metallic, copper on the inside and
stainless on the outside.
3. All joints on the hermetic TXV (inlet, outlet
and equalizer lines) are brazed.
4. Bi--metallic connections heat up very
quickly.
1. Pump down the unit per paragraph 6.4.
2. Remove cushion clamps located on the inlet and out-
let lines.
3. Unbraze the equalizer connection (1/4”), the outlet
connection (5/8”) and then the inlet connection
(3/8”). See Figure 6-19. Be careful to protect the in-
sulation on the heaters and their wires.
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
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 6-18 for bulb placement.
3. Insulate the thermal bulb.
4. Braze inlet connection to inlet line, see Figure 6-19.
5. Braze outlet connection to outlet line.
6. Reinstall the cushion clamps on inlet and outlet lines.
7. Braze the equalizer connection to the equalizer line.
8. Check superheat (refer to step 6.14.1).
6.14.3 Semi--Hermetic Valve Replacement
a. Removing Expansion Valve
1 Pump down the unit per paragraph 6.4.
2 Remove insulation (Presstite) from expansion valve
bulb and power assembly and then remove thermal
bulb from the suction line (see Figure 6-18) .
3 Loosen flare nut and disconnect equalizing line from
expansion valve.
4 Remove capscrews and lift off power assembly and
remove cage assembly. Check for foreign material in
valve body.
5 The thermal bulb is located below the center of the
suction line (4 o’clock position). This area must be
clean to ensure positive bulb contact.
b. Installing Expansion Valve
CAUTION
If the thermostatic expansion valve is found
to be in need of replacement, then the
power head and cage assembly are to
replaced as a pair. They are a matched pair
and replacing one without the other will
affect the superheat setting.
1 Replace all gaskets, making sure to lightly coat with
oil. Insert cage and power assembly and bolts.
Tighten bolts equally. Fasten equalizer flare nut to
expansion valve.
2 Leak check the unit per paragraph 6.5. Evacuate
and dehydrate unit per section 6.6. Add refrigerant
charge per section 6.7.
3 Clean suction line with sandpaper before installing
bulb to ensure proper heat transfer. Strap thermal
bulb to suction line, making sure bulb is placed firmly
into the indentation of the suction line. See
Figure 6-18 for bulb placement.
4 Check superheat. (Refer to paragraph 6.14.2 step
6.14.1 ) Container box temperature should be at
--18
°
C (0
°
F).
6.15 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.
6.15.1 Evaporator Coil Replacement
a. Pump unit down. (Refer to paragraph 6.4.)
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 per paragraph 6.5. Evacuate
the unit per paragraph 6.6 and add refrigerant charge
per paragraph 6.7.
6.15.2 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.
Содержание 69NT40--541--200 TO 299
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