Fresh Food Defrost Heating Element; Drain Tube/Tray Defrost Heating Element - Dometic NDA1402 Service Manual

10.6 fresh food defrost Heating element

The fresh food heater is located behind the cooling fins
along the back wall of the refrigerator section. When ac-
tivated, it will provide 40 watts of heat to melt any ice or
frost that may have accumulated during normal operation.
To check the resistance of the heater, remove the cover
from the main control board on the back of the refrig-
erator. Remove the P5 harness cable from the lower pc
board. Measure the resistance between pin 6 (red wire)
and pin 3 (black wire). The resistance reading should be
3.6 Ohm's +/- 10%. The resistance can also be checked
at the inter-connection box just above the cooling fins.
The refrigerator should be defrosted prior to this test to
avoid erroneous readings. Frost/Ice could conduct cur-
rent hiding an open circuit in the heater. A faulty heater
may display an error code on the front display panel. See
section 11 for trouble shooting error codes.
Another test would be to check the amp draw. A simple
method is to remove the wires from the thermo fuse and
place a meter inline. Enter the service mode, and proceed
to test #7. The amp draw should be 3.3 +/- 10%.
note:
The interior light must be off when performing
this test as to avoid a false value of the actual amp draw
of the heater.
10.7 drain tube/tray defrost Heating ele-
ment
The drain tube/tray heater is placed at the bottom of the
plastic cover, housing the freezer cooling plate. This heat-
er is on at all times during the defrosting of the freezer
and fresh food compartments and will remain on for short
periods of time at the end of defrosting to help assure
water does not refreeze in the drain line. To check the
resistance of the heater, remove the cover from the main
control board on the back of the refrigerator. Remove the
P5 harness cable from lower pc board. Measure the resis-
tance between pin 5 (white wire) and pin 2 (yellow wire).
The resistance should be 13.3 Ohm's +/- 10%. The re-
sistance can also be checked at the inter-connection box
along the back wall behind the ice maker assembly. The
refrigerator should be defrosted prior to this test to avoid
erroneous readings. Frost/Ice could conduct current hid-
ing an open circuit in the heater. A faulty heater may dis-
play an error code on the front display panel. See section
11 for trouble shooting error codes
Drain tube/tray heater installed.
Drain tube/tray heater removed
In some cases during the install or replacement of the
drain tube/tray heater, the portion that extends into the
drain tube may become folded over or bunched up. When
the heater is activated, this may cause a short and cause
the heater to become open. A faulty heater may display
an error code on the front display panel. See section 11
for trouble shooting codes.
Verify the portion extending into the
drain tube is not looped or folded
over to itself.
Another test would be to check the amp draw. A simple
method is to remove the wires from the thermo fuse and
place a meter inline. Enter the service mode, and proceed
to test #9. The amp draw should be .9 +/- 10%.
note:
The interior light must be off when performing
this test as to avoid a false value of the actual amp draw
of the heater.
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