Sub-Zero UC-24 series Service Manual page 18

Electronic Control System
Monitor Compressor Run Duration, Displays If Service is Needed
The microprocessor observes the state of the compressor relay to determine the length of compressor run time (See
Figure 3-24). If the compressor runs 100% (Freezer = 6 hours, Refrigerator = 4 hours), an error code is logged (EC
40, or EC 50, respectively), and defrost will be initiated, but SERVICE will not flash.
If several 100% compressor run periods occur, and the door was not opened during the last excessive compressor
run period, and the temperature in the zone is not able to fall half way between the set point and the low off-set,
then SERVICE will flash (See Figure 3-25).
NOTES:
• After the problem is corrected, the error code must be cleared from memory, otherwise a non-flashing "SERVICE"
will display constant on the LCD. See "Clearing Non-Flashing "SERVICE" and Error Codes" later in this section.
• If the unit is ever switched OFF then back ON, the compressor will not energize for at least three (3) minutes.
This three (3) minute minimum OFF time is used to protect the compressor and its electricals.
HIGH VOLTAGE SCHEMATIC
Compressor
ORANGE
relay closed,
allowing
power to
compressor.
This is
observe by
micro-
processor.
J6
J4
J5
Figure 3-25. Service Flashing if several 100% compressor run periods occurred, the door was not opened
during last excessive run period, and temperature is not able to fall half way between set point & low off-set.
#7003933 - Revision B - November, 2007
115 VOLTS
60 CYCLES
L1
GRAY/WHITE
J2
WHITE
P4
PIN 1
BLACK
P3
MAIN BOARD
PURPLE
P1
BLUE
P2
PIN 1
PIN 1
PIN 1
PIN 1
J3
ORANGE
Figure 3-24. UC-24C Signal Trace Schematic - Compressor Run
Under Counter (UC-24) Series
NEUTRAL
WHITE
OVERLOAD
PROTECTOR
GRAY/WHITE
CONDENSER FAN
RED
DEFROST HEATER
R55 OHMS
ORANGE
REF LIGHT SWITCH
REF (TOP) LIGHT
THERMAL
FUSE ICEMAKER
WHITE
BLACK
TAN
3-18
WHITE
RUNNING
CAPACITOR
(WHEN
USED)
COMPRESSOR
COMPRESSOR
STARTING
M
RELAY
WHITE
WHITE
M
REF FAN MOTOR
WHITE
M
WHITE
WHITE
ICEMAKER
VALVE
WHITE
R160 OHMS