Service manual

29
Installation and Service Manual
COMPONENT DIAGNOSTICS
SAFETY THERMO-DISC / FAN CYCLE CONTROL
Ice Thickness Control Adjustment
1. Adjustment to the bridge thickness is done at the
circuit board. On the bottom (front) of the board
you will find either two round black potentiometers
or a set of 8 DIP switches. Please follow the in-
structions below for the particular type of board
you have. For optimum ice production and har-
vest, it is recommended that a 5mm (3/16") bridge
thickness be obtained. In any event, you must not
have a bridge thickness less than 3mm (1/8").
2. TO ADJUST A BOARD WITH TWO POTENTI-
OMETERS (3 RELAY):
If the machine had been running properly prior to
failure of the thermistor, run the machine through
one complete cycle without making any adjustment
in the bridge thickness. If further adjustment is
necessary, adjust the FINE (right) potentiometer
first. Turn the dial to a higher number for a thinner
bridge thickness. Turn the dial to a lower number
for a thicker bridge thickness. Always wait for one
complete cycle after making any adjustment be-
fore readjusting the machine. If further adjustment
is necessary beyond that obatinalbe with the fine
adjustment, you may utilize that COARSE (left)
potentiometer. This dial should only be moved one
marked graduation at a time. One mark is equiva-
lent to about 3/4 turn of the fine dial. The coarse
dial should be moved one mark then fine tuned
with the fine dial.
3. TO ADJUST A BOARD WITH 8 DIP SWITHCES
(4 RELAY)
If the machine had been running properly prior
to failure of the thermistor, tun the machine
through one complete cycle without making any
adjustment in the bridge thickness. If further
adjustment is necessary, adjust the DIP
swithces. To have a thicker bridge, turn the next
(right) switch "on". To have a thinner bridge, turn
the next (left) switch "off". It is acceptable to have
all the switches either on or off. Follow the wedge
above the switch case for thicker or thinner
bridge. To turn the swithc "on" push the top of
the swithc down. If further adjustment is neces-
sary, you may adjust the potentiometer. This "pot"
is located to the left of the 8 DIP switch case.
Remember this is a coarse adjustment. Move
this pot no more than one (1) graduation at a
time. You will then have to adjust the DIP
switches for proper thickness.
SAFETY THERMO-DISC
The thermo-disc is a safety control located on the
evaporator inlet for 3 relay siphon systems. This disc is
insulated to prevent ambient air from effecting the opera-
tion. The disc is non-adjustable and set to open at 120
o
F/
49
o
C (closes at 95
o
F/35
o
C) evaporator inlet line tempera-
ture. The disc prevents the cuber from over heating if the
product should remain in a hot gas harvest cycle for any
reason.
On a remote cuber, a thermo-disc(s) is wired in series
with the compressor contactor. The thermo-disc will pro-
vide a second high temperature safety cut-out device to
protect the ice maker during the pump down cycle when
the circuit board and thermistor does not control the unit.
To Check the Safety Thermo-Disc
Disconnect the thermo-disc RED leads from the ma-
chine. With an OHM meter check for continuity - if ther is
none, replace the disc if temperature of disk is below 90
o
F
(32
o
C).
Should thermo-disc be open becuase of hi-temp safety
cut-out, you may reclose the disc by manually holding the
contactor closed to run the compressor and cool the evapo-
rator inlet line to be certain the thermo-disc will reclose. Do
not hold the contactor in for more than 30 seconds.
FAN CYCLE CONTROL
This is a high side pressure control that cycles the con-
denser fan motor off at approximately 180 PSI (12.4Bars)
and on at 250 PSI (17.2Bars). Its purpose is to maintain a
minimum head pressure for proper operation in low ambi-
ent conditions.
Remote systems and dual evaporator models utilize
fan cycle controls.
To check:
Install a high side gauge to the hi-side service valve.
DO NOT attach to the receiver valves. Operate the system
and observe the pressures the fan motor cycles. If the cy-
cling pressure is more than +/- 10% out of the control range,
replace the control - it is nonadjustable.
NOTE: CONCAVED SIDE OF BLADE IS FACING FAN
MOTOR ON ALL AIR COOLED SERVEND
CUBERS AND REMOTE CONDENSERS.