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Defrost Heater
Defrost heaters are resistive loads and should be
tested for proper resistance as indicated on the
schematic wiring diagram, using a volt/ohm meter.
However, a visual inspection should also be made
and the heater replaced if any of the following
conditions are observed:
• Element is open
• Glass tube is broken
• Glass tube is opaque with green or black
coating inside
• Element coils are bunched together
• End caps or terminals are deteriorated, burnt or
corroded
When replacing a defrost heater, avoid handling the
glass tube with bare hands. Even small quantities
of salt, or other contaminants from the hands
deposited on the surface of the glass will increase
the brittleness, which could result in premature
failure of the heater. Handle the heater by the end
caps. If it should be necessary to grasp the glass
tube, clean it afterward with a damp paper towel or
approved glass cleaner.
The defrost heater can be checked with a volt/ohm
meter at the EDC board or electro-mechanical
defrost control, depending on the model. If an open
circuit is detected, isolation of the defrost heater will
be needed to verify that the defrost heater is faulty.
Use the schematic for proper check points and
component values.
(Continued next page)
5 Amp Inline Fuse
The 5 Amp Fuse opens the line (120 VAC) side of the
defrost circuit and protects the refrigerator from
a shorted/grounded heater. The inline fuse can be
diagnosed by unplugging the connectors at the
defrost heater and the fuse connector. Use an ohm
meter to check continuity.
5 Amp Inline Fuse Removal
1. Disconnect power to the refrigerator.
2. Access the evaporator section.
3. Disconnect the fuse from the defrost heater and
connector located above the evaporator.
If an open fuse is discovered, observe and check
the defrost heater, wire connections at the defrost
heater, and at the defrost control (EDC board/
electro-mechanical defrost control). If faults are
found, replace or repair the components. If no
component or wiring issues are found, only replace
the fuse.
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