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IV. Service Diagnosis
A. 10-Minute Diagnostic Procedure
The 10-minute check out procedure is basically a sequence check which can be used
at unit start-up or for system diagnosis. Using this check out procedure will allow you
to diagnose electrical system and component failures in approximately 10 minutes
under normal operating conditions of 70°F (1°C) or warmer air and 50°F (10°C) or
warmer water temperatures. Before conducting a 10 minute checkout, check for correct
installation, proper voltage per unit nameplate and adequate water supply. As you go
through the procedure, check to assure the components energize and de-energize
correctly. If not, those components and controls are suspect.
1) Turn power off and access the icemaker's control box. Clear any ice from the bin
control actuator located in the bin.
) Turn power on and place the control switch in the "ICE" position. A 5 second delay
occurs. The red "POWER OK" LED and the green "BC CLOSED" LED on the control
board come on.
3)
One Minute Fill Cycle
– LED 4 is on. The fill water valve is energized. After 1 minute,
the control board checks for a closed lower float switch. If the lower float switch is
closed, the harvest cycle begins. If closed, continue to step 4. If the lower float switch
is open, the fill water valve will remain energized through additional 1 minute fill
cycles until water enters the sump and the lower float switch closes (low water safety
protection during initial start up and at the end of each harvest).
Diagnosis:
If the fill
water valve does not open, check for no supply voltage at water valve terminals, bad
coil, or plugged screen or external filter (no water flow). If the reservoir fills, but the unit
fails to start harvest, check for open lower float switch (see "II.F.3. Float Switch Check
Procedure") or bad 1 minute timer in control board. See "II.C.4. Control Board Check
Procedure."
4)
Initial Harvest Cycle
– LEDs 1, 4 and are on. The contactor coil energizes to start
the compressor and fan motors, the hot gas valves energize (also energizing the
X1 relay), the harvest water valve energizes and the fill water valve de-energizes. The
harvest water valve is open during harvest for a maximum of 6 minutes or the length of
harvest minus 50 seconds, whichever is shorter. The pump motor energizes and runs
for the last 50 seconds of harvest.
The evaporator warms and the thermistor senses 48°F (9°C). The control board then
receives the thermistor's 3.9 k
Ω
signal and turns operation of harvest over to the
harvest countdown timer. The last 50 seconds of the harvest countdown timer, the
harvest water valve de-energizes and the water pump energizes, (LED 4 goes off and
LED 3 comes on). When the harvest countdown timer completes, the freeze cycle
starts.
Diagnosis:
Check if evaporator is warming up, compressor and fan motors are
on, hot gas valves are open, harvest water valve open. If these are okay, next check
for at least 48°F (9°C) on the suction line. If the evaporator is cool, check for inlet
water too cold or liquid line valves stuck open. If the suction line is at least 48°F (9°C),
disconnect the thermistor at the white K3 connector on the control board and check for
resistance of 3.9 k
Ω
or less. If different, see "II.D. Harvest Control – Thermistor," for
check procedure. Replace if necessary. If resistance is 3.9 k
Ω
or less, reconnect the
thermistor to the white K3 connector on the control board. If harvest does not terminate
within 3 minutes, replace the control board.
