6
−
9
T-364
6.13 EVAPORATOR COIL & HEATER ASSEMBLY
The evaporator section, including the evaporator 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 con-
denser 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 6.4) Refer to
paragraph 6.6.1.
WARNING
Always turn OFF the unit circuit breaker
(CB-1) and disconnect main power supply
before working on moving parts.
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. Unsolder the two coil connections, one at the distribu-
tor and the other at the coil header.
e. Disconnect the defrost temperature sensor (see
f. Remove middle coil support.
g. Remove the mounting hardware from the coil and re-
move the coil.
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 back to a terminal block. If a
heater failure occurs during a trip, the heater set
containing that heater may be disconnected at the
terminal block. When isolating an individual heater it is
important to ensure it is disconnected from the terminal
block and the heater contactor to isolate it completely.
The next Pre-trip (P1) will detect that a heater set has
been disconnected and indicate that the failed heater
should be replaced. To remove a heater, do the
following:
WARNING
Always turn OFF the unit circuit breaker
(CB-1) and disconnect main power supply
before removing electrical parts.
a. Before servicing unit, make sure the unit circuit break-
ers (CB-1) 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.
To replace a heater, do steps a through e in reverse.
Heater Element
Bracket
Retainer
Figure 6
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7 Heater Arrangement
Summary of Contents for 69NT40-561-201
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