Multiplex MB-8-1, Technician'S Handbook

Page: 94 / 178

94 Part Number STH034 3/12
Refrigerated Cabinet Operation
Default temperature setpoint = 36° F with a ±2° F
Differential
NORMAL OPERATION
The microprocessor control board controls the cabinet
temperature based on the input received from the
cabinet temperature thermistor. The thermistor value
is compared to the control board setpoint. When the
reach-in temperature is equal or greater than the
setpoint (plus half the differential) the compressor
relay closes provided the following conditions are
satisfied:
•
Power has been uninterrupted to the control board
for a 3 minute period.
OR
•
The 3 minute compressor time delay has expired.
The delay period starts after the compressor has
run and then cycles off.
The compressor relay opens when the reach-in
temperature is less than the setpoint (minus half the
differential).
EVAPORATOR AND CONDENSER FAN MOTOR
OPERATION
The condenser fan motor and compressor share the
same relay. The evaporator fan motor relay is
energized continuously and the evaporator fan cycles
off only during cleaning cycle.