Hoshizaki KM-901MAH Service Manual page 31

(2) "G" Control Board: Auxiliary Code U-1 and Later
At startup, a 5-second delay occurs while the control board conducts an internal timer
check. A beep occurs when the control switch is moved to the "ICE" position. The red
LED indicates proper control voltage and remains on unless a control voltage problem
occurs. The green LEDs 1 through 4 energize and sequence from initial startup as
listed in the table below. Note that the order of the LEDs from the outer edge of the
control board is 1, 4, 3, 2. For details, see "II.B. Sequence of Operation."
Sequence Step
1-Minute Fill Cycle
Harvest Cycle
Harvest Pump Timer 1, 3, 2
Freeze Cycle
Pump-Out Cycle
The built-in safeties shut down the unit and have alarms as listed below.
No. of Beeps
(every 3 sec.)
1 High Evaporator Temp.
(temperature > 127°F)
2 Harvest Backup Timer
(harvest > 20 min. for two cycles
in a row)
3 Freeze Timer
(freeze > freeze timer setting for
two cycles in a row)
To reset the above safeties, press the "ALARM RESET" button with the power supply on.
6 Low Voltage
(92Vac±5% or less)
7 High Voltage
(147Vac±5% or more)
Legend: Comp–compressor; FM–fan motor; FMR–fan motor-remote; F/S–float switch;
HGV–hot gas valve; HM–headmaster (C.P.R.); LLV–liquid line valve; PM–pump
motor; TXV–thermostatic expansion valve; WRV–water regulating valve;
WV–inlet water valve
Energized
LED
Components
4 WV
1, 4, 2 Comp, FMR, WV, HGV
Comp, FMR, PM, HGV
1 Comp, FM/FMR, PM,
LLV
1, 4*, 3, 2 Comp, FMR, WV*, PM,
HGV
Type of Alarm
(53°C)
Min.
2 minutes 20 minutes 3 to 5 minutes
0 seconds 50 seconds harvest pump timer
5 minutes freeze timer
setting
10 seconds 20 seconds *pump-out timer
Check for harvest problem (stuck HGV or relay), hot
water entering unit, stuck HM, or shorted thermistor.
Check for open thermistor, HGV not opening, TXV or
LLV leaking by, low charge, inefficient Comp, or WRV
leaking by.
Check for F/S stuck closed (up), WV leaking by, HGV
leaking by, PM not pumping, TXV not feeding properly,
LLV not opening, low charge, HM not bypassing, or
inefficient Comp.
Red LED turns off if voltage protection operates.
The control voltage safeties automatically reset when
voltage is corrected.
31
Time LEDs are On
Max. Avg.
1 minute
setting
30 to 35 minutes
setting
Notes