Hoshizaki KM-630MAH, KM-630MWH, KM-630MRH service manual Evaporator is Frozen UP, Thermistor

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.
	f) Water Supply Line	1.			Too small; requires 3/8”	1.	Increase Water Line size.
					OD line dedicated per
					machine.
	g) Water Filter (if	1.			Flow rate too small.	1.	Replace with filter with
	installed)						larger flow rate.

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