Component Description - Scotsman MC 15 Service Manual

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Freeze Cycle
Average Discharge
Pressure A/C: 16÷18 bars (225÷250 psig)
Average Discharge
Pressure W/C:
Suction Pressure End
Freeze Cycle: 1.6÷1.7 bar (22÷24 psig)
REFRIGERANT CHARGE (R 404 A)
Air Cooled
MC 15 640 gr
MC 45 1300 gr
MC 45 (60 Hz) 1040 gr
NOTE. Before charging the refrigerant system
always check the type of refrigerant and
quantity as specified on the individual ice
machine dataplate.
The refrigerant charges indicated are related
to average operating conditions.
WARNING. As R 404 a is a band of different
types of refrigerants it is imperative to
charge the system only in liquid phase in
order to avoid to alter their mix-up
percentage.
COMPONENTS DESCRIPTION
A. EVAPORATOR TEMPERATURE
SENSOR
The evaporator temperature sensor probe,
located in contact with the evaporator serpentine,
detects the dropping of the evaporator tempera-
ture during the freezing cycle and signals it by
supplying a current flow to the micro processor of
P.C. BOARD.
According to the current received, the evaporator
sensor supplies power to the P.C. BOARD first,
° °
when it reachs 0 C (32 F), second at -15
in this second case it supply power to the electronic
timer built into the P.C. BOARD so that it may
take control of the fength of the 2nd phase of
freezing cycle.
The length of the timed phase is pre-f ixed by the
setting of the keys 1, 2, 3 and 4 of the DIP
SWITCH.
17 bars (240 psig)
Water Cooled
500 gr
700 gr
560 gr
° °
C (5 F);
The activation of the electronic timer (-15°C -
5°F) is monitored by the lighting up of the RED
LED placed in the front of the P.C. BOARD.
This lighting up occures usually in the mid period
of the freezing cycle and signals the switching
from the first to the second phase of the freezing
cycle.
NOTE. Whenever, after 15 minutes from the
beginning of the freezing cycle, the
evaporating temperature have not yet
reached the value of 0 ° C (32 ° F), the P.C.
BOARD switches OFF the machine with the
BLINKING of RED LED.
B. CONDENSER TEMPERATURE SENSOR
The condenser temperature sensor probe,
located within the condenser fins (air cooled
version) or in contact with the tube coil (water
cooled version) detects the condenser tempera-
ture variations and signals them by supplying
current, at low voltage, to the P.C. BOARD.
In the air cooled versions, in relation to the
different current received, the micro processor of
the P.C. BOARD supplies, through a TRIAC, the
power at high voltage to the fan motor so to cool
the condenser and to reduce its temperature.
In case the condenser temperature rises and
reaches 70°C (1 60°F) - on air cooled models - or
62°C (145°F) - on water cooled models - the
current arriving to the micro processor is such to
cause an immediate and total stop of the machine
operation.
C. ICE BIN LEVEL LIGHT CONTROL
The electronic ice bin level control, located into
the storage bin, has the function to stop the
operation of the ice machine when the light beam
between the light source and the sensor is
interrupted by the ice cubes stored into the bin.
When the light beam is interrupted the Bin Full
YELLOW LED starts to blink; in case the light
beam is constantly interrupted for more than 60
seconds, the ice machine stops with the glowing-
up of the Bin Full YELLOW LED to monitor the
situation of ice bin full.
The 60 seconds of delay prevent that an ice
scoop movement or the ice dropping through the
ice chute (interrupting for a while the light beam)
can stop the operation of the unit.
Six seconds after the scoop out of the ice (with
the resumption of the light beam between the two
infrared sensor of ice level control) the ice machine
restarts again with the extinguishing of the
YELLOW LED.
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