Page 21
Page 21
PRINCIPLE OF OPERATION
How it works
In the SCOTSMAN cube ice makers the water
used to make the ice is kept constantly in
circulation by an electric water pump which primes
it to the spray system nozzles from where it is
diverted into the inverted mold cups of the
evaporator. A small quantity of the sprayed
water freezes into ice; the rest of it cascades by
gravity into the sump assembly below for
recirculation.
FREEZING CYCLE
The hot gas refrigerant discharged out from the
compressor reaches the condenser where, being
cooled down, condenses into liquid.
Flowing into the liquid line it passes through the
drier filter, then it goes all the way through the
capillary tube where, due to the heat exchanging
action, it looses some of its heat content so that
its pressure and temperature are lowered as
well.
Next the refrigerant enters into the evaporator
serpentine (which has a larger I.D. then the
capillary) and starts to boil off; this reaction is
emphasized by the heat transferred by the
sprayed water.
The refrigerant then increases in volume and
changes entirely into vapor.
The vapor refrigerant then passes through the
suction accumulator (used to prevent that any
small amount of liquid refrigerant may reach the
compressor) and through the suction line. In both
the accumulator and the suction line it exchanges
heat with the refrigerant flowing into the capillary
tube (warmer), before to be sucked in the
compressor and to be recirculated as hot
compressed refrigerant gas.
The freezing cycle is controlled by the evaporator
temperature sensor (which has its probe in
contact with the evaporator serpentine) that
determines the length of its first portion of the cycle.
When the temperature of the evaporator
serpentine drops to a pre-set value (small Red
LED ON steady) the evaporator sensor probe
changes its electrical resistance allowing a low
voltage current (15 volts) to flow to the P.C. BOARD
which in turn activates an electronic timer.
The timer, which is built-in the P.C. BOARD, takes
over from the evaporator temperature sensor,
the control of the freezing cycle up to its completion.
NOTE. The change of the electric potential of
the evaporator sensor with the consequent
activation of the timer (Time mode) is signalled
by the glowing-up of the RED LED located in
the front of the P.C. BOARD.
ATTENTION. In case, after 15 minutes
from the beginning of the freezing cycle,
the temperature of the evaporator sensor
probe is higher then 0
°
C (32
°
F) - small
Red LED still OFF - (shortage of refrigerant,
inoperative hot gas valve, etc.) the P.C.
BOARD switch OFF immediately the unit
with the simultaneous blinking of the
WARNING RED LED.
The length of this timed portion of the freezing
cycle is pre-fixed and related to the setting of the
first four DIP SWITCH keys.
The DIP SWITCH keys setting is made in
consideration of the type of condenser used and
size of ice cubes.
DIP SWITCH FACTORY SETTING COMBINATIONS (PER MODEL AND VERSION)
FREEZING CYCLE
DEFROST CYCLE
15/30"
AIR/WATER
DEFROST CYCLE
ADD. TIME
TAB. A
DIP SWITCH
1
2
3
4
ACM 106 A
ACM 106 W
ACL 106 A
ACL 106 W
ACS 126-176 A
ACS 126-176 W
ACM 126 A
ACM 126 W
ACL 126 A
ACL 126 W
ACM 176 A
ACM 176 W
ACL 176 A
ACL 176 W
ACS 206 A
ACS 226 A
ACM 206-226 A
ACM 206-226 W
ACL 206 A
ACL 206 W
5
6
7
8
9
10
ON
ON
OFF
OFF
ON
ON
ON
ON
ON
ON
ON
ON
OFF
OFF
ON
ON
ON
ON
OFF
OFF
ON
ON
OFF
OFF
ON
ON
ON
ON
ON
ON
ON
ON
OFF
OFF
OFF
OFF
ON
ON
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
ON
ON
OFF
OFF
OFF
OFF
ON
ON
OFF
OFF
OFF
OFF
ON
ON
ON
ON
ON
ON
ON
ON
OFF
OFF
ON
ON
ON
ON
ON
ON
ON
ON
ON
ON
ON
ON
OFF
OFF
OFF
OFF
ON
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
ON
ON
ON
ON
ON
ON
ON
ON
OFF
OFF
ON
ON
ON
ON
ON
ON
ON
ON
ON
ON
OFF
OFF
ON
ON
ON
ON
OFF
ON
ON
ON
ON
ON
ON
ON
ON
ON
ON
ON
ON
ON
ON
ON
ON
ON
ON
ON
ON
ON
ON
ON
ON
ON
ON
ON
ON
ON
ON
ON
ON
ON
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
ON
ON
ON
ON
ON
ON
OFF
ON
OFF
ON
OFF
ON
OFF
ON
OFF
ON
OFF
ON
OFF
ON
ON
ON
OFF
ON
OFF
