6--14
T-334
1
2
4
3
1. Copper Tube
(Apply heat for 10-15 sec-
onds)
2. Bi-metallic Tube
Connection (Apply heat for
2-5 seconds)
3. Braze Rod
(’Sil-Phos” = 5.5% Silver,
6% Phosphorus)
4. Use of a wet cloth is
not necessary due to rapid
heat dissipation of the
bi-metallic connections
Figure 6--14 Hermetic Thermostatic Expansion Valve Brazing Procedure
f. Disconnect the defrost temperature sensor (see
Figure 2--2 from the coil.
g. Remove middle coil support.
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
The heaters are wired directly back to the contactor and
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.
6.14 ECONOMIZER, UNLOADER, LIQUID
INJECTION, AND EXPANSION BYPASS
SOLENOID VALVES
a. Replacing the Coil
NOTE
The coil may be replaced without removing the
refrigerant.
1
2
3
4
1. Slotted Screw
2. Washer
3. Coil
4. Enclosing Tube and Body
Figure 6--15 Economizer Solenoid Valve (ESV),
Liquid Injection Valve (LIV) and Expansion Bypass
Solenoid Valve (XBSV)
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