Operating instructions

TM 11574A-OI
3-24
7
Unsolder the two coil connections, one at the distributor and the other at the coil
header.
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 per Refrigeration leak checking paragraph 3-10b(2)(e).
Evacuate the unit per Evacuation and dehydration paragraph 3-10b(3), and add
refrigerant charge per Refrigeration charge paragraph 3-10b(4).
(b) 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 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, perform the following.
1
Before servicing unit, make sure the unit circuit breakers (CB-1 & CB-2) and the start-
stop switch (ST) are in the OFF position, and that 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 Table 1-1 for heater resistance values. Once the set containing the failed
heater is determined, cut the splice connection 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.
(c) Manual Defrost Switch Inspection. This maintenance procedure does not exist in the
commercial manual. It is to be developed at a later date.
1
Manual Defrost Switch Removal. This maintenance procedure does not exist in the
commercial manual. It is to be developed at a later date.
2
Manual Defrost Switch Replacement. This maintenance procedure does not exist in
the commercial manual. It is to be developed at a later date.
(d) Defrost Temperature Sensor Inspection. This maintenance procedure does not exist in
the commercial manual. It is to be developed at a later date.
1
Defrost Temperature Sensor Removal. This maintenance procedure does not exist
in the commercial manual. It is to be developed at a later date.
2
Defrost Temperature Sensor Replacement. This maintenance procedure does not
exist in the commercial manual. It is to be developed at a later date.
(e) Heat Exchanger Inspection. This maintenance procedure does not exist in the
commercial manual. It is to be developed at a later date.
1
Removing Heat Exchanger. This maintenance procedure does not exist in the
commercial manual. It is to be developed at a later date.