Hoshizaki IM-500SAA User Manual

AM SERVICE TRAINING

Featuring the

IM-500SAA

80047 9/10/13

All IM models have similar sequence of operation. This manual is designed as a

generic IM Training manual.

The Hoshizaki IM series ice machine

uses a horizontal evaporator design
which forms a square cube shape with a
small dimple.

20mm

2

A standard 120-volt power cord (field
supplied) provides the electrical
connection. The unit is designed to
operate on a separate 20-amp circuit.

The water supply connection is 1/2” FPT
fitting and is located at the top right side
of the unit. A minimum 1/4” water line
is required for proper operation.

The drain connection is 3/4” FPT fitting
located on the right rear of the unit. A
standard 3/4” MPT fitting can be used to
connect this drain.

The ABS water plate sprays water up
into the evaporator cells to form the
square IM cube.

3

The moveable water pan assembly
includes the water plate, reservoir
pan, and pump motor assembly.
Tension springs connect two cam
arms to the water plate assembly. An
actuator motor rotates the cam arms
to raise and lower the water pan
during the ice making cycle.

4

The horizontal evaporator and water
distribution system are unique to the
Hoshizaki IM series. The IM-500 makes
ice on a horizontal evaporator and uses
R-404a refrigerant.

The IM-500SSA sequence of operation
will be explained in the following pages.

5

r

Thermisto

The IM-500SAA unit uses a
combination thermistor and control
board to control the sequence of
operation.

SOFT START:

When the toggle switch is placed in the
“ON” position and the bin control calls
for ice, the unit will begin in the soft
start the display will say “on” and the
hot gas valve will open after 30 seconds
the initial harvest cycle begins,(if the
reset switch is pressed during the 30 sec.
standby time the unit will skip soft start
and immediately starts operation).
Starting the unit in harvest allows the
compressor to start up in basically an
unloaded condition, greatly extending
the life of the compressor. This
operation is common among all
Hoshizaki cube icemakers.

WATER PAN OPENS/HARVEST:

During the initial harvest, the
compressor, hot gas valve and the
actuator motor starts to open, after 20
seconds the water valve will energize to
supply defrosting water for a specified
time. (The time varies depending on the
incoming water temperature above or
below 48

water temp. is not detected and
assumed to be below 48º

ºF(9ºC) also in initial cycle the

F (9ºC)

resulting in a longer defrosting water
supply time.
The opening backup timer starts
counting when the water pan starts to
open if the hall IC (magnetic switch)
does not turn on within 3 min. the
display will show “EE” and the unit
stops for 60 minutes, if it reoccurs after
the unit resumes display will show “EE”
and the unit shuts down and (records as
“E3” in the error history.

Hall IC Switch is located on the
motor backside. (Magnetic Switch)

As soon as the pan starts to open the defrost
backup timer starts, if the thermistor mounted
on the evaporator does not reach the defrost
completion temperature before the timer times
out at 30 min. the display will show “E2” and
the unit stops. (if the HGV does not open this
could also give you an “E2” error)

The harvest cycle is controlled by thermistor
when the defrost completion temperature of

18.5º C or more is reached the HGV closes, the

fan motor starts, and the water pan starts
closing.
As before there is a timer that starts as soon as
the water pan starts to close. If the hall IC
(magnetic Switch) does not turn on within 3
min. the machine will stop and give a “EE”
error and the machine shuts down for 60
minutes if the error reoccurs after restart the
unit will shut down again and again shows
“EE” (recorded as ‘E4” in the error history).

NOTE: in the initial cycle or when the water is

below 48º F (9ºC), the water valve will open to

supply defrosting water for 10 second after the
water pan starts to close.

To check the resistance between thermistor
leads, follow the steps below.

1) Disconnect the connector CN13 on the
board.

2) Remove the screw and the thermistor holder
on the evaporator.

3) Immerse the sensor part in a glass containing
ice and water for 2 or 3 minutes.

4) Check the resistance between thermistor
leads. Normal reading is

within 5 to 7 kΩ
Replace the thermistor if it is
outside the normal reading.

6

7

WATER PAN CLOSES/FREEZE:

When the water pan closes and the hall
IC turns on the water valve opens to
supply ice making water for a specific
time. The supply time varies between
startup, reset, and end of bin control
cycle between partial flush and full
drain.

NOTE Full drain flush: After a freeze

cycle ends the unit drains all remaining
water out of the tank and refills for the
next freeze cycle.

Partial drain flush: (default setting)

After a freeze cycle ends, the unit leaves
remaining water in tank and adds water
for the next cycle.

After water has been supplied the pump
motor starts, after 30 seconds the
thermistor senses the temperature that
will be added with a predetermined
offset value and used as the water
temperature for the freeze cycle, pan
opening, defrost, and pan closing cycle.
The freeze cycle is considered to be
100% complete when the predetermined
target and the integrated values are
reached. To reduce ice forming on the
water pan when the freeze completion
rate reaches 100% with an ambient

temperature below 86º F (30ºC), the hot

gas valve opens and closes two times to
raise the water pan temperature and the
actuator motor starts to open the water
pan. The freeze cycle is not considered
complete and the pump motor and fan
motor continue. The unit will continue
to cycle between freeze and harvest until
the bin control opens, signaling a full
bin or until power is interrupted

8

The IM-500SAA uses a mechanical bin
control located on the right rear side of
the ice drop zone. This control will open
when ice pushes against the switch, if the
switch stays open for more than 10
seconds the machine will start the bin
control cycle, starts and the machine will
shut down after the next defrost cycle.

After the bin control stays closed for
more than 80 seconds the bin control
cycle will end and the machine will
restart.(the hot gas valve opens 30
seconds before the icemaker restarts)

After the bin control cycle ends (or when
the power supply is turned on), the water
pan starts to open.

When the water pan opens and the hall
IC turns on, the bin control cycle starts
after 10 seconds and the ice maker stops.

.