Sub-Zero UC-24 series Service Manual page 11

Under Counter (UC-24) Series
FUNCTIONS OF ELECTRONIC CONTROL SYSTEM
The following few pages explain monitoring, regulating and controlling functions of the electronic control system.
Display Zone Temperatures
The temperature signals from the thermistors in the refrigerator and freezer compartments are monitored by the
microprocessor and then displayed on the LCD. Though the compartment air temperature does fluctuate, the LCD
displays the "average" temperature (See Figure 3-16).
NOTE: If zone temperature changes, temperature display will change by one degree per minute.
Supply Power to the Lighting System
Power is supplied to the lighting system through the control board when the unit is switched ON by pressing the
POWER key. With the door open, the light switch allows power to the lights. (See Figure 3-17).
NOTES:
• Power to the lights is monitored by the microprocessor to control evaporator fan motor operation.
• When in Sabbath Mode, the lighting system is disabled. Sabbath Mode was covered earlier in this section.
• The accent lighting system in the model UC-24B is fed direct from L-1.
HIGH VOLTAGE SCHEMATIC
NOTE: Light switch position
monitored to control fan operation.
ORANGE
J2
PIN 1
MAIN BOARD
PIN 1
J6
J4
PIN 1
PIN 1
J5
Figure 3-17. UC-24B Signal Trace Schematic (High Voltage) of Lighting System
Figure 3-16. Display Zone Temperatures
115 VOLTS
60 CYCLES
L1
P4 WHITE
P3 BLACK
PURPLE
P1
P2
PIN 1
J3
ORANGE
REF LIGHT
ORANGE
"average" temperature displayed
REF LIGHT SWITCH
LIGHT TUBE SWITCH
NEUTRAL (UC-24B ONLY)
WHITE
NOTE: Accent lighting system
in UC-24B is fed direct from L1.
1. Power supplied
OVERLOAD
to control board.
PROTECTOR
CONDENSER FAN
RED
2. Power supplied to lighting sys-
tem unless unit is switched
OFF, or in Sabbath Mode.
REF (TOP)
SWITCH LIGHT
3-11
Electronic Control System
WHITE
PINK
LIGHTS
RUNNING
CAPACITOR
COMPRESSOR
COMPRESSOR
STARTING
M
RELAY
M
M
REF FAN MOTOR
#7003933 - Revision B - November, 2007
WHITE
(WHEN
USED)