Evaporator Is Frozen Up; Low Ice Production - Hoshizaki KM-500MAF Service Manual

2. EVAPORATOR IS FROZEN UP

PROBLEM
[1] Freeze cycle a) Float Switch
time is too
long.
b) Water Solenoid
c) Controller Board
[2] All ice formed a) Evaporator
on Evaporator b) Water Supply Line
does not fall
into bin in c) Water Solenoid
harvest cycle.
d) Ambient and/or
e) Line Valve
f) Thermistor
g) Controller Board
[3] Others a) Spray Tubes
b) Water System
c) Refrigerant
d) Expansion Valve
e) Hot Gas Solenoid
f) Water Supply Line
g) Water Filter (if
POSSIBLE CAUSE
Valve
Valve
water temperature
Valve
installed)
1. Leads short-circuit or
defective switch.
2. Float does not move freely.
1. Diaphragm does not close.
1. Defective.
1. Scaled up.
1. Water pressure too low.
1. Dirty mesh filter or orifice.
2. Diaphragm does not close.
1. Too cool.
1. Continues to open in
harvest cycle.
1. Out of position or loose
attachment..
1. Defrost Timer is set too
short.
2. Defective.
1. Clogged.
2. Out of position.
1. Dirty.
1. Undercharged.
1. Bulb out of position or
loose attachment.
2. Defective.
1. Coil winding opened.
2. Plunger does not move.
3. Wiring to Hot Gas Valve.
1. Too small; requires 3/8"
OD line dedicated per
machine.
1. Flow rate too small.
38
REMEDY
1. Check and replace.
2. Clean or replace.
1. Check for water leaks
with icemaker off.
1. See "II.2[e] CHECKING
CONTROLLER BOARD."
1. Clean.
1. Check and get
recommended pressure.
1. Clean.
2. Check for water leaks
with icemaker off.
1. Increase temperature.
1. Check operation in
harvest cycle and replace.
1. See "V. 11. REMOVAL
AND REPLACEMENT OF
THERMISTOR."
1. Adjust longer, referring
to "II. 2. [d] CONTROLS
AND ADJUSTMENT, 2)
Defrost Timer."
2. See "II. 2.[e] CHECKING
CONTROLLER BOARD."
1. Clean.
2. Place in position.
1. Clean.
1. Check for leaks and
recharge.
1. Place in position.
2. Replace.
1. Replace.
2. Replace.
3. Check for loose
connection or open, and
replace.
1. Increase Water Line size.
1. Replace with filter with
larger flow rate.