Regulate Zone Temperature And Fan-Assisted Off-Cycle Defrost - Sub-Zero 424HAG/O-2 Service Manual

Electronic Control System

Regulate Zone Temperature and Fan-Assisted Off-Cycle Defrost

When the thermistor in the refrigerator compartment reaches high off-set temperature, calling for cooling, the evapo-
rator fan is energized, but the compressor is not allowed to run until the thermistor on the evaporator reaches 38°F
(3°C). (See Figure 3-56)
If either drawer is opened while the evaporator fan is operating, the microprocessor will detect the power signal to
the lights and cut power to the fan.
Though compartment air temperatures will fluctuate, the LCD will only display average temperature.
NOTE: If compartment temperature exceeds either high or low offset (Ex: drawer is left open), temperature display
will change by one degree per minute.
NOTE: If refrigerator compartment thermistor is faulty, compressor operation defaults to 20 minutes ON, 40 minutes
OFF cycling, EE appears in left of LCD, SERVICE will flash and Error Code 05 will be logged.
NOTE: If evaporator thermistor is faulty, the compressor will not energize until zone air temperature exceeds high
offset by 5°F (3°C). SERVICE flashes and Error Code 06 is logged.
NOTE: When in Sabbath Mode, the refrigerator compartment thermistor still controls compressor operation, except
there is a random 15 to 25 second delay before the compressor is energized.
HIGH VOLTAGE
LOW VOLTAGE
THERMISTER
CABINET
1. Thermistor at high off-set
temp. calling for cooling.
DRAWER
CONTROL
Figure 3-56. Signal Trace - Regulate Refrigerator Zone Temperature
#3758410 - Revision C - May, 2014
NEUTRAL WHITE
ORANGE
WHITE
J2
P4
BLACK
P3
PURPLE
P1
BLUE
J6
5. Compressor
P2
energized.
MAIN
J4
RED
BOARD
J3
J5
DPDT RELAY
NEUTRAL WHITE
ORANGE
2. No Power
to lights.
BLUE W/ WHITE
BLUE W/ WHITE
MAIN
BOARD
BLACK
WHITE
RED
YELLOW
ORANGE
BLUE
Wine Storage
Wine Storage
L1 NEUT
115 VOLTS
60 CYCLES
BLACK
PURPLE
OVERLOAD
PROTECTOR
RED
DOOR SWITCH
YELLOW
6 5 4
DOOR SWITCH
ORANGE
1 3
3. Evap fan energized.
3-30
Series
Series
2
2
(400- )
(400- )
NEUTRAL WHITE
CONDENSER FAN MOTOR
M
2000 Ω
MULLION HEATER
COMPRESSOR
STARTING RELAY
M
COMPRESSOR
EVAPORATOR FAN MOTOR
M
TOP DRAWER LIGHTS
LOWER DRAWER LIGHTS
BLUE /W BLACK
BLUE /W BLACK
THERMISTER
EVAPORATOR
4. Evap Thermistor
above 38°F (3°C).