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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.
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.
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.
NOTE
The coil may be replaced without removing the
refrigerant.
6.16 ECONOMIZER, UNLOADER, LIQUID INJEC-
TION AND OIL RETURN SOLENOID VALVE
a. Replacing the Coil
1 Be sure electrical power is removed from the unit.
Disconnect leads. Remove top screw and washer.
Lift off coil. (See Figure 6-14 or Figure 6-15)
2 Verify coil type, voltage and frequency of old and new
coil. This information appears on the coil housing.
T-322
b.
Replacing Valve Internal Parts (Unloader
Solenoid Only)
1 Pump down the unit. Refer to paragraph 6.4.
2 Be sure electrical power is removed from the unit.
Disconnect leads. Remove top screw and washer.
Lift off coil. (See Figure 6-14)
3 Remove the top screw (see Figure 6-14), washer ,
and coil assembly.
4 Loosen the enclosing tube locknut.
5 Remove enclosing tube and locknut assembly. The
gasket is inside the enclosing tube.
6 Remove seat disc from inside of body and check for
obstructions and foreign material.
7 Place the seat disc into the valve body with the small-
er diameter end facing up.
8 Install stem and plunger.
9 Place the enclosing tube locknut over the enclosing
tube. Install spacer over enclosing tube making sure
it is seated properly in the enclosing tube locknut.
Tighten enclosing tube locknut to a torque value of
2.78 mkg (20 ft-lb). Do not overtighten.
10 Install coil assembly, washer and top screw.
11 Evacuate and dehydrate the system. (Refer to sec-
tion 6.6.) Charge unit with refrigerant per section 6.7.
12 Start unit and check operation.
c.
Replacing Valve
1 To replace the unloader, liquid injection or economiz-
er valve, pump down the unit. Refer to paragraph
6.4. To replace the oil return valve, remove the refrig-
erant charge.
2 Be sure electrical power is removed from the unit.
Disconnect leads. Remove top screw and washer.
Lift off coil. (See Figure 6-14 or Figure 6-15)
3 Unbraze valve from unit and braze new valve in
place
4 Install coil. Evacuate low side and place unit back
in operation. Check charge.
1
2
3
4
5
6
7
8
9
Figure 6-14. Unloader Solenoid Valve
6-10
1.
Top Screw
2.
Washer
3.
Coil
4.
Locknut
5.
Enclosing Tube
6.
Gasket
7.
Stem and Plunger
8.
Seat Disc
9.
Body
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