Scotsman NU150 Service Manual page 17

NU Undercounter Ice Machine Service Manual
Note：
If defrost cycle does not start 60 Minutes after
the starting of freezing cycle, the unit will
automatically identify as freezing overtime and
automatically enter into the defrost cycle. If the
freezing overtime occurs to the ice maker 5
times in a row (caused by short of refrigerant,
abnormal operation of defrost valve, etc.),
freezing indicator light-ZBLX+R1LX lights will
be blinking(on the PC board, it shows light
SL1 blinking and light ZBL1 blinking). At this
time, the user needs to disconnect the unit
and contact with the service agent.
During refrigeration cycle, the pressure range
of high-pressure side is:
NU100： 15～26 bar （218psi～377psi）
NU150： 15～27bar （218psi～391psi）
NU220： 15～26 bar （218psi～377psi）
NU300： 15～27bar （218psi～391psi）
The pressure of the high-pressure side is
controlled by the condensation temperature
sensor located at the condenser.
condensation temperature senor senses the
condensation temperature exceeds the set
value, it will feed back to the PC board which
will control the operation of fan.
Contrarily, when the condensation temperature
senor is lower than
condensation temperature, it will feed back to
the PC board which will control the outage of
fan.
If the
the set value of
Notes:
If condensation temperature probe senses
the temperature is higher than 70℃(160°F),
the unit will stop caused by the startup of
protection device, while the R2LX on display
board will be illuminating(light SL1 on PC
board will quickly blink), warning user of too
high condensation temperature.
After the condensation temperature is lower
than 70℃(160°F),
power button before the unit restarts, and
switch on the ice maker, then waiting for 3
Minutes. After 3 Minutes of water injection,
the ice maker is working normally.
Reasons for abnormal operation as follows:
Condenser is block;
Air temperature is higher than 40 ℃
(100°F);
To avoid abnormal operation and risk of
the unit, the user should cut off the power
upon one of the above reasons.
At the start of freezing cycle, pressure of
refrigeration suction side or low-pressure side
is rapidly reduced; the pressure will be
gradually reduced
increases. When the ice cube is completely
formed in the ice mold, pressure reaches:
NU100： 5～2 bar （58psi～29psi）
NU150： 5～2 bar （58psi～29psi）
NU220： 5～2 bar （58psi～29psi）
NU300： 5～2 bar （58psi～29psi）
Overall length of freezing cycle is between
15-40 Minutes.
16
How the ice maker works
switch off the unit by the
as the ice thickness