© 2009 Viking Preferred Service
51
Defrost Heater
The unit uses a heater to help remove ice build
up during the defrost cycle. When the defrost
terminator closes, voltage is supplied to the heater
via the control board.
To access the defrost heater, open freezer door
and remove (see Evaporator Fan Access section).
Remove ice maker (see Access Ice Maker Module,
Motor and Support section) remove evaporator fan
cover and back wall (see Evaporator Fan Access
section). The defrost heater is now accessible.
With the main power switch OFF, the defrost Heater
can be tested by removing the orange wire off of
terminal E6 on the HV board. Using an ohm meter,
check the brown wire and Neutral and you should
read approximately 30 Ω.
During the defrost cycle Line voltage passes
through the Defrost Terminator the into terminal
E5 (orange wire). With the defrost heater relay
activated, the voltage exits the HV board from
Terminal E6 (orange) to the heating element.
If voltage is present at E5 but not at E6, then the
Defrost relay is open. If there is 0 volts
At E5, then the terminator is open.
Defrost Terminator
The defrost terminator is a bimetal switch that is
normally open. Below 20º +/- 8.5º F, the terminator
is closed. In order to test, first switch the main
power switch to OFF, then locate the brown wire on
E5 of the HV board. Unplug the wire and check for
continuity between the brown wire and the black
wire at E10. In the defrost cycle, this circuit will
supply Line voltage to the defrost relay.
To access the defrost terminator, open freezer door
and remove (see Evaporator Fan Access section).
Remove ice maker (see Access Ice Maker Module,
Motor and Support section) remove evaporator fan
cover and back wall (see Evaporator Fan Access
section). The defrost terminator is clipped to the
evaporator and is now accessible.
To avoid risk of electrical shock, personal injury, or death, disconnect electrical power to unit using power
switch before servicing. Wires removed during disassembly must be replaced on proper terminals to insure
correct earth ground and polarization. After servicing, reconnect power using power switch.
Service Diagnostics and Procedures–Disassembly
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