Service manual

6-- 14T--318
1. Pump down the unit per paragraph 6.4.
2. If TXV replacement is to be performed from the front
of the unit, open the upper right (EFM#1) access
panel (see Figure 2-1) and remove the evaporator
fan motor.
3. Remove cushion clamp that secures the valve body
to the bracket.
4. Unbraze the equalizer connection (1/4”), the outlet
connection (5/8”), and then the inlet connection
(3/8”). See Figure 6-21. Be careful to protect the in-
sulation on the heaters and their wires.
5. If TXV replacement is being performed from the front
of the unit, remove the access panel for the bulb.
6. Open the insulation flap. Flap is secured with Velcro
(Item 3, Figure 6-22).
7. Loosen the thumb screw and slide the bulb, out by
pulling it towards the front of the unit.
1
2
3
4
5
6
1. Hermetic Expansion Valve Bulb
2. Insulation
3. Insulation Flap
4. Velcro strip
5. Bulb Clamp
6. Thumb Screw
Figure 6-22 Hermetic Thermostatic Expansion
Valve Bulb Location
b. Installing the Expansion Valve
1. Braze inlet connection to inlet line (see Figure 6-21).
2. Braze outlet connection to outlet line.
3. Braze the equalizer connection to the equalizer line.
4. Reinstall the cushion clamp.
5. Thread the thermal bulb through the opening above
the evaporator coil (see Figure 2-2), and slide it un-
der the strap and secure the thumb screw. Close the
insulation flap. Reinstall bulb access panel.
6. Check superheat (refer to step 6.14.1).
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 drain pan hose is routed behind the condenser fan
motor and compressor. The drain pan line 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
The heaters are wired directly back to the contactor . If a
heater failure occurs during a trip, the heater set
containing that heater may be disconnected at the
contactor.
The next pre-trip will detect that a heater set has been
disconnected and indicate that the failed heater should
be replaced. To replace a heater, do the following:
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 is discon-
nected.
b. Remove the upper back panel.
c. Determine which heater(s) need replacing by check-
ing resistance of each heater set. Refer to paragraph
2.3 for heater resistance values. Once the set con-
taining the failed heater is determined, cut the splice
connection and retest to determine the actual failed
heater(s).
d. Remove hold-down clamp securing heater(s) to coil.
e. Lift the bent end of the heater (with the opposite end
down and away from coil). Move heater to the side
enough to clear the heater end support and remove.