Hoshizaki KM-900MAF, KM-900MWF, KM-900MRF3 Evaporator Is Frozen Up, Low Ice Production

2. EVAPORATOR IS FROZEN UP

PROBLEM	POSSIBLE CAUSE				REMEDY
[1] Freeze cycle	a) Float Switch	1.	Leads short-circuit or	1.	Check and replace.
time is too			defective switch.
long.		2.	Float does not move freely.	2.	Clean or replace.
	b) Water Solenoid	1.	Diaphragm does not close.	1. Check for water leaks
	Valve				with icemaker off.
	c) Controller Board	1. Defective.		1.	See “II.2[e] CHECKING
					CONTROLLER BOARD.”
[2] All ice formed	a) Evaporator	1.	Scaled up.	1.	Clean.
on Evaporator	b) Water Supply Line	1.	Water pressure too low.	1.	Check and get
does not fall					recommended pressure.
into bin in	c) Water Solenoid	1.	Dirty mesh filter or orifice.	1.	Clean.
harvest cycle.	Valve	2.	Diaphragm does not close.	2.	Check for water leaks
					with icemaker off.
	d) Ambient and/or	1.	Too cool.	1. Increase temperature.
	water temperature
	e) Line Valve	1.	Continues to open in	1.	Check operation in
			harvest cycle.		harvest cycle and replace.
	f) Thermistor	1.	Out of position or loose	1. See “V. 11. REMOVAL
			attachment.		AND REPLACEMENT OF
					THERMISTOR.”
	g) Controller Board	1.	Defrost Timer is set too	1.	Adjust longer, referring
			short.		to “II. 2. [d] CONTROLS
					AND ADJUSTMENT, 2)
					Defrost Timer.”
		2. Defective.		2.	See “II. 2.[e] CHECKING
					CONTROLLER BOARD.”
[3] Others	a) Spray Tubes	1. Clogged.		1. Clean.
		2.	Out of position.	2.	Place in position.
	b) Water System	1.	Dirty.	1.	Clean.
	c) Refrigerant	1. Undercharged.		1.	Check for leaks and
					recharge.
	d) Expansion Valve	1.	Bulb out of position or	1.	Place in position.
			loose attachment.
		2. Defective.		2.	Replace.
	e) Hot Gas Solenoid	1. Coil winding opened.		1. Replace.
	Valve	2.	Plunger does not move.	2. Replace.
		3.	Wiring to Hot Gas Valve.	3.	Check for loose
					connection or open, and
					replace.

3. LOW ICE PRODUCTION

PROBLEM		POSSIBLE CAUSE	REMEDY
[1]	Freeze cycle	a) See chart 1 - [3], and check dirty Air Filter or Condenser,	ambient or water
	time is long.	temperature, water pressure, Water Regulator or refrigerant charge.
		b) See chart 2 - [1], and check Float Switch, Water Solenoid Valve or Controller
		Board.
[2]	Harvest cycle	a) See chart 2 - [2], and check Controller Board, Thermistor, Evaporator, ambient
	time is long	and/or water temperature, water supply line, Water Solenoid Valve, Line Valve.

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