– 17 –
Defrost Heater and Fill Tube Heater
Run diagnostic mode
14
to test the defrost cycle.
(
See
Diagnostics and Service Information
.)
The termination temperature for the defrost cycle
is 45°F at the evaporator thermistor.
The defrost heater and fi ll tube heater
are
supplied with 120 VAC only during the defrost
cycle. The fi ll tube heater is in parallel with the
defrost heater, and both are in series with the
fuse link. Check for 120 VAC at K4 on the power
supply board while the unit is in test mode 14.
To access the defrost heater and/or fi ll tube
heater, remove the evaporator cover (see
Evaporator Cover
).
The defrost heater is rated at 100 watts and has a
resistance value of 121
Ω
.
This fi ll tube heater is rated at 3.5 watts and has a
resistance value of 3.8K
Ω.
To remove and replace the fi ll tube heater:
1. Disconnect the fi ll tube heater at the plug-in
connector (see photo).
2. Cut the heat-shrink tubing from the fi ll tube
heater.
3. Slide the fi ll tube heater from the fi ll tube as
shown.
To remove the defrost heater:
1. Disconnect the defrost heater at the plug-in
connector.
Disconnect
Slide Off
Disconnect
2. The evaporator heater is held in place by
metal tabs on the drain trough. Carefully
lever-open the metal tabs as shown.
3. Carefully remove the defrost heater from the
evaporator.
Extremely Important:
When installing a new
defrost heater, ensure that it rests securely on
the bottom of the drain trough. Failure to do this
will result in water freezing in the drain hole and a
repeat service call.
Metal Tab
4. Wind the new fi ll tube heater around the fi ll
tube.
5. Cover the fi ll tube heater with heat-shrink
tubing, then apply heat to ensure a tight fi t.
6. Connect the fi ll tube heater at the plug-in
connector.
Drain Trough
Evaporator Heater
