Scotsman AF Series Service Manual page 22

Page 22
the MICRO-PROCESSOR of the P.C. Board
which energizes, through a TRIAC, the Fan
Motor in ON-OFF mode.
When the opposite situation occures, i.e. the
condenser temperature gets below the pre-fixed
ACCUMULATOR
CAPILLARY TUBE
COMPRESSOR
FAN MOTOR
limit, the temperature sensor changes again its
electrical resistance reducing therefore the
current flow to the P.C. Board to cause a
temporary stop of the Fan Motor.
On the water cooled versions, the refrigerant
head pressure is kept at the constant value of
9.5 bars (138 psig) - 17 bar (245 psig) on AF 30
only by the metered amount of water passing
through the condenser which is regulated by the
action of the Water Regulating Valve that has its
capillary tube connected to the liquid refrigerant
line. As pressure increases, the water regulating
valve opens to increase the flow of cooling water
to the condenser.
FIG. 6
WATER
LEVEL
GEAR MOTOR
CONDENSER TEMP.
EVAPORATOR TEMP.
ICE LEVEL CONTROL
L
L
N
N
EVAPORATOR
DISCHARGE LINE
RESET
13
13
ROTATION
12 12
T<1°C
11 11
10
10
9
9
1
1
TRANSF.
2
2
NOTE. In case the condenser temperature probe
s enses that the condenser temperature has
° °
rised to 70 C (160 F) - on air cooled versions
° °
- or 60 C (140 F) - on water cooled versions -
for one of the following abnormal reasons:
CLOGGED CONDENSER (Air cooled version)
INSUFFICIENT FLOW OF COOLING
WATER (Water cooled version)
FAN MOTOR OUT OF OPERATION (Air
cooled version)
AMBIENT TEMPERATURE HIGHER THEN
° °
43 C (110 F)
it causes the total and immediate SHUT-OFF
of the machine (drive motor keeps on working
by 3' delay then stops) in order to prevent the
unit from operating in abnormal and dangerous
conditions. When the ice maker stops on
account of this protective device, there is a
simultaneous glowing of the RED LED, warning
the user of the Hi Temperature situation. The
machine will remain in OFF mode for one hour
then it will restart automatically. In case the unit
trips OFF again in alarm for 3 times in 3 hours,
the machine SHUTS OFF DEFINITIVELY.
After having eliminated the source of the
excessive con-denser temperature, to restart
the ice machine it is necessary to unplug and
plug in again. The RED LED starts blinking
and three minutes later the flaker unit resume
its normal operating mode. The condenser
temperature sensor has a further safety
function which consist in preventing the unit
from operating in Lo-ambient conditions i.e.
when the condenser body temperature -
equivalent to the ambient temperature - is
° °
lower then 1 C 34 F (Fig.6). As soon as the
ambient temperature rises up to 5 ° C (40 ° F)
the PC Board will automatically restarts the
machine through the three minutes delay time.
8
8
7
7
RELAYS
6
6
5
5
4
4
3
3
TRIAC
Page 22
CONTACTOR COIL
GEAR MOTOR
FAN MOTOR
ELECTRONIC
CARD