Carrier 69NT40-561-300, Operation And Service Manual

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7–17 T-365
2. With power OFF and power plug removed, remove the screws securing the panel covering the evaporator
section (upper panel).
3. Disconnect the defrost heater wiring.
4. Remove the mounting hardware from the coil.
5. Unsolder the two coil connections, one at the distributor and the other at the coil header.
6. Disconnect the defrost temperature sensor (refer to Section 7.25 ) from the coil.
7. Remove middle coil support.
8. After defective coil is removed from unit, remove defrost heaters and install on replacement coil.
9. Install coil assembly by reversing above steps.
10.Leak check connections. Evacuate and add refrigerant charge.
7.13.2 Evaporator Heater Replacement
The heaters are wired directly back to the contactor and if a heater failure occurs during a trip, the heater set con-
taining that heater may be disconnected at the contactor.
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 breakers (CB-1 & CB-2) and disconnect main power supply
before working on moving parts.
1. Before servicing unit, make sure the circuit breakers (CB-1 and CB-2) and start-stop switch (ST) are in the
OFF position, and the power plug is disconnected.
2. Remove the upper back panel.
3. Determine which heater(s) need replacing by checking resistance of each heater set. Refer to Section 3.3
for heater resistance values. Once the set containing the failed heater is determined, cut the splice connec-
tion and retest to determine the actual failed heater(s).
4. Remove hold-down clamp securing heater(s) to coil.
5. 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, perform steps 1 through 5 in reverse.
Figure 7.13 Heater Arrangement
7.14 EVAPORATOR FAN AND MOTOR ASSEMBLY
The evaporator fans circulate air throughout the container by pulling air in the top of the unit. The air is forced
through the evaporator coil where it is either heated or cooled and then discharged out the bottom of the refrigera-
tion unit into the container. The fan motor bearings are factory lubricated and do not require additional grease.
Heater Element
Bracket
Retainer