Hoshizaki KM-901MAH, KM-901MWH, KM-901MRH/3 Control Board Auxiliary Code U-1 and Later

(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		LED	Energized		Time LEDs are On
			Components	Min.	Max.	Avg.
1-Minute Fill Cycle	4		WV			1 minute
Harvest Cycle		1, 4, 2	Comp, FMR, WV, HGV	2 minutes	20 minutes	3 to 5 minutes
Harvest Pump Timer	1, 3, 2		Comp, FMR, PM, HGV	0 seconds	50 seconds	harvest pump timer
						setting
Freeze Cycle	1		Comp, FM/FMR, PM,	5 minutes	freeze timer	30 to 35 minutes
			LLV		setting
Pump-Out Cycle		1, 4*, 3, 2 Comp, FMR, WV*, PM,		10 seconds 20 seconds		*pump‑out timer
			HGV			setting

The built-in safeties shut down the unit and have alarms as listed below.

No. of Beeps	Type of Alarm	Notes
(every 3 sec.)
1	High Evaporator Temp.	Check for harvest problem (stuck HGV or relay), hot
	(temperature > 127°F)	water entering unit, stuck HM, or shorted thermistor.
	(53°C)
2	Harvest Backup Timer	Check for open thermistor, HGV not opening, TXV or
	(harvest > 20 min. for two cycles	LLV leaking by, low charge, inefficient Comp, or WRV
	in a row)	leaking by.
3	Freeze Timer	Check for F/S stuck closed (up), WV leaking by, HGV
	(freeze > freeze timer setting for	leaking by, PM not pumping, TXV not feeding properly,
	two cycles in a row)	LLV not opening, low charge, HM not bypassing, or
		inefficient Comp.
To reset the above safeties, press the "ALARM RESET" button with the power supply on.
6	Low Voltage	Red LED turns off if voltage protection operates.
	(92Vac±5% or less)	The control voltage safeties automatically reset when
7	High Voltage	voltage is corrected.
	(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

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