Wiring Schematic (Adaptive Defrost) - Viking VCBB360R Service Manual

Electronic Function Description
WARNING: To avoid electrical shock which can cause severe personal injury or death,
disconnect power to refrigerator using power switch before servicing. Wires removed
during disassembly must be replaced on proper terminals to insure correct grounding
and polarization. After servicing, reconnect power using power switch.
Adaptive Defrost Theory of Operation
After designated compressor run time, refrigeration cycle is interrupted and electronic control sends a low
voltage signal to defrost relay coil (def D1).
Powering the relay coil closes contact (D1) completing high voltage circuit to defrost heater through
closed defrost terminator (closes at 15 F).
Isolator, which is part of high voltage PC board, recognizes presence of line voltage to defrost heater and
sends low voltage signal to electronic control.
Electronic control keeps count of number of minutes, defrost terminator remains closed (opens at 48 F).
Length of time defrost terminator is closed determines if the next defrost cycle advances by 4 hours of
compressor run, stays at the same interval, or delays by 4 hours of compressor run.
If defrost terminator does not open before 29 minutes, defrost cycle is automatically terminated be
electronic control and refrigeration cycles will resume after 6 minutes dwell time.
IMPORTANT:
showroom switch is OFF, the
isolator sees line voltage which
keeps the electronic controller
from signaling the evaporator fan
motor or compressor relay coils
and also keeps the fresh food and
condensate evaporation fans off.
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When the