Customer complains that unit is low production.
HOSHIZAKI CARE
TECH-TIPS
Danny Moore Hoshizaki America, Inc. Volume 104
Editor 618 Hwy. 74 South April 7, 1994
Peachtree City, GA 30269
Care Facsimile: (800) 843-1056
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Cuber Production Check
Spring has sprung and hot weather is on the way. Higher temperatures outside means more ice usage inside.
A properly sized unit will provide adequate
capacity in these peak periods of use. However, this is not always the case.
In the peak summer time, ambient conditions and inlet water temperatures are at their highest and
unfortunately, the ice machine output will be at its lowest. This usually results in a customer complaint if
the unit was not sized properly for peak periods. At this time the unit should be checked thoroughly for
proper operation. Be sure to check that the evaporator, condenser, air filter, water filter and water valve are
clean before conducting a production check. Also utilize the 10 minute checkout procedure to assure proper operation.
The steps for a cuber production check are as follows:
1) Time a complete cycle from the beginning of one freeze cycle to the beginning of the next freeze cycle. 2)
Catch all of the ice from this freeze cycle and weigh the total batch. 3) Divide the total minutes in a 24 hour day
(1440) minutes) by the complete cycle time in minutes to obtain the number of cycles per day. 4) Multiply the
number of cycles per day by the cycle batch weight for the cuber production per 24 hours.
Once you calculate the production, check the incoming water temperature, and ambient condensing
temperature of the cuber and cross reference the Data Specification Chart in the unit Service Manual to see if
the calculation falls within 10% of the specification. If not within specifications, additional trouble shooting
is required to find out why. For the most accurate production check, a normal freeze cycle should be checked. If the evaporator compartment has been opened for service or if the unit has been cut off for a long period of time, the first freeze
cycle will be longer than normal. Timing this cycle can result in an inaccurate production check. To avoid this,
start the unit and allow it to operate for 10 minutes in the freeze cycle, unplug the float switch lead and cause
the unit to cycle into harvest mode. Start timing as soon as the next freeze begins. Also remember that the
evaporator compartment must be closed during the production check. Removing the front cover to check
the ice buildup during a production check will allow heat into the evaporator and will effect the total cycle time
and actual production.
A complete inspection and production check on a KM Cuber can easily be completed in approximately 1 hour.
This is an effective tool to help you prove to the customer that the unit is indeed performing according to specifications.
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THERMOSTATIC BIN CONTROL CHECK
OUT Hoshizaki cubers utilize and adjustable thermostatic bin control. The bin control is factory set
to shut down ice production within 6 to 10 seconds after ice contacts the thermostatic capillary bulb. This
capillary bulb is mounted on either a drop down bin control bracket which is located in the bin or on the
inside wall of the ice drop zone. The thermostatic bin control is a simple pressure
operated switch which closes when the temperature of the capillary bulb rises above 45°F and opens when ice
contacts the bulb causing the temperature to drop below 45°F. To check the thermostatic bin control
utilize a volt/ohm meter. If the bin control is not installed in a unit, you can bench check it with the ohm meter.
Place ice on the bulb and check the terminals for an open circuit or “maximum” resistance. Warm the bulb
with your hand and check the terminals for a closed circuit or “zero” resistance. If the bin control is installed
in the unit, with proper voltage applied to the machine, switch the toggle switch to the ice making position.
Warm the bulb with your hand to assure the switch is closed and check across the terminals and from each
terminal to ground for 115VAC. A good control will read “zero” VAC across the terminals and 115VAC
from each terminal to ground. If you read zero VAC across the terminal and do not read 115 VAC from
each terminal to ground, the bin control contacts are open and the control is defective or the bulb temperature is
below 45°F. A defective bin control can have sticking contacts (opened or closed), or has lost the bulb charge which
will keep the contacts open and not allow the unit to start up. If the contacts stick closed . the unit will not
shut down when ice contacts the bulb which will cause ice to back up into the ice drop zone and possibly cause
a freeze up situation.
The bin control bulb must be mounted properly to contact the ice pyramid in the storage bin. The bulb
mounting bracket is ABS plastic and is included with the KM replacement bin control. This bracket was
redesigned in 1991 and will replace the original stainless bin control bracket.
The bin control should be checked at start up, when the installation is complete, to make sure it operates
properly. A properly. A properly adjusted bin control will shut down the unit within 6 to 10 seconds after ice
is placed on the bulb. An adjustment may be needed if the unit is installed in a high altitude area. Be sure to
warm the bulb with your hand to make sure the unit starts back up properly.
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FLAKER SEQUENCE OF OPERATION
(New flaker with periodic flush)
The Hoshizaki Flaker utilized a solid state sequence timer board to switch the components on and off as
needed. The sequence is as follows: With proper voltage and water supplied to the Flaker and the flush
and ice switch is in the ice position, power is supplied to the inlet water valve. The unit will not start unless the
reservoir is full and both floats on the dual float switch are closed (in the up position). The operation is then
turned over to the bin control. If the bin control is closed and calling for ice, the gear motor and condenser
fan motor and condenser fan motor are energized. One minute later, the compressor starts. As the refrigeration
system cools the water in the evaporator, ice will form within 2 to 5 minutes. This depends on the inlet water
temperature and ambient conditions. Ice production will continue until the bin control is satisfied (opens).
The shut down process is very simple. On the F-650, F-1000 and F-2000 units, the entire unit shuts down
within 6 seconds after the bin control switch opens. On the F-250 and F-450, 90 seconds after the bin control
switch opens, the compressor stops, one minute later the gear motor and condenser fan motor stop.
This sequence of operation is accomplished through a series of timers within the solid state timer board.
Beginning with the F-450 and larger flakers, a periodic flush cycle is included. A 12 hour timer will cycle the
unit down and open the flush valve which allows the complete water system to drain down. The unit will
remain off for 15 minutes which allows any ice remaining in the evaporator to melt and flush the
evaporator to melt and flush the evaporator walls and mechanical seal out. The inlet water valve is not
energized during this flush period. This flush period is unique to Hoshizaki Flakers and will
provide cleaner operation and longer bearing life.
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HOSHIZAKI CARE
TECH-TIPS
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CONTACTORS
A magnetic contactor is a large relay with contacts designed to handle the higher current flow of the
compressor. A typical contactor will have 1 or more primary contacts sized to carry a heavy current load. It
may also have 1 or more auxiliary or secondary contacts to be used for smaller loads or controls.
You will find two different contactors used in the KM series. Hoshizaki part number 428393-01 is used in all
KM models through the KM-1200 series. Part number 438215-01 is used on KM-1600 and larger
units. This multi-purpose contactor has three sets of primary and four sets of auxiliary contacts. It is also
used on the F-2000 flaker.
Sometimes in three phase applications, a larger contactor is used together with current type overload
protection. This combination is found in part number 440360-01 used on the KM-2400 SRE3.
In the KM series, the contactor serves to operate two components. When the 115 volt coil is energized, the
primary contacts close to complete the compressor circuit. The auxiliary contacts open
to de-energize the crankcase heater found on all remote units.
Diagnosing a bad contactor is simple once you understand that it is a mechanical switching device.
When voltage is supplied to the designated coil terminals, the magnetic coil armature moves the
mechanical linkage to open or close the contacts. Contactor problems fall into one of three categories,
open or grounded coil, sticking or broken linkage, and pitted, burnt, or welded contacts.
If the contactor does not switch with proper voltage applied to the coil, check the coil first. Disconnect the
power and terminals and use an ohm meter to check the coil for continuity. If the coil is good, you can usually
hear the linkage snap when power is supplied. A broken or stuck linkage will not allow any of the primary
or auxiliary contacts to switch. This can be checked by using an volt/ohm meter to check across the contacts
appying basic electrical trouble-shooting techniques. Lastly, pitted, burnt, or welded contacts are a
symptom of a possible problem with the component in series with those contacts. Pitted or burnt contacts can
cause a voltage drop. These contacts can be carefully dressed with a contact file or fine sandpaper and
cleaned with contact cleaner to correct the voltage drop. If not corrected this drop can cause further
problems with the corresponding component. Welded contacts are caused by the excessive heat
related to high amp draw. The problem causing the high amp draw must be corrected when the contactor is changed out.
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LEAK DETECTION METHODS by David Brown
Leak detection has become more important now, with present EPA rules and the high cost of replacement
refrigerants. The industry offers several methods for leak detection.
Soap bubbles is the oldest and cheapest method. Applying the soap solution with a dauber or spray bottle
to joints and fittings will quickly locate many refrigerant leaks.
The “sniffer” halide torch, halogen electronic, and pump methods detect the chlorine present in
CFC/HCFC refrigerants. The halide torch flame will turn green when chlorine gas is sniffed through the sniffer
hose. The halogen electronic and pump detectors have a pump probe that can sniff out leaks as low as .5
oz/year. Sniffer type detectors are less effective in areas where a high concentration of refrigerant is present.
Recent models of pump type detectors are designed to detect new HFC’s also.
Note : When using these detectors to check for leaks in the evaporator area of an ice machine, the sniffer can
pick up traces of chlorine gas released from the water. This could lead to the mis-diagnosis of an evaporator
leak. Moisture in the probe tip can give the same results. Other types of electronic leak detectors are available.
The corona discharge system is a recent design that uses a high voltage arc in the sensing tip to detect gases that
are denser than air. The ultrasonic leak detector senses the high frequency “hiss” or sound produced as gas
escapes the leak. This system works well where high concentrations of gases exist. There are certain noises
however, that will limit its effectiveness. Since the ultrasonic detects a hissing sound, it can be used if the
refrigeration system is in a vacuum or is pressurized with nitrogen. Detection by sound also makes this
system directional so that leaks can be pinpointed easier.
Pressurizing the system with dry nitrogen has always been an acceptable means to assist in leak detection.
Proper safety practices must be followed when using dry nitrogen. Always throughly evacuate all nitrogen
from the system prior to recharging with refrigerant. Remember that oxygen should never be used to
pressurize a system. It is acceptable with the EPA to add a small amount of refrigerant with the nitrogen
charge (HCFC’s are preferred) to assist in locating the leak with a sniffer type system.
Some system additives like red and florescent dyes are available now to help pinpoint leaks. Testing is not
complete as to the long term effects of these dyes on the system. Hoshizaki does not recommend
the use of any system additives at this time. As the role of new refrigerants expands, new technology
in leak detection will surface. Watch the technical publications for future improvements that will help you
find difficult leaks.
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WHY LONGER CYCLES ?
Without a doubt Hoshizaki KM series cubers have the longest cycle time of any comparable cuber on the
market today. Is this a problem? Not if you look at the benefits of longer cycles.
The KM series was deliberately designed with longer cycles and a larger ice drop weight. The truth is,
longer cycles mean fewer cycles a day. Fewer cycles relate directly to longer component life and better running efficiency.
Consider this, for every freeze cycle there is a harvest period. While the harvest period does function
to release the ice, it decreases efficiency by stopping the refrigeration process. Also, harvest puts additional
stress on the compressor. This is a fact of life with a hot gas defrost system. Fewer cycles in the KM series
means fewer harvest periods a day. Fewer harvest periods means more time to make ice, less stress on the
compressor, longer life and better efficiency. This logic applies to every component in the ice machine
that cycles on and off between freeze and harvest. Fewer starts and stops relate to longer life.
Does longer cycle times mean longer diagnosis time? The answer to this question is no. A technician who
understands the KM sequence of operation can diagnosis a defective component using the ten minute
check-out procedure quickly and easily. This longer cycle theory has been proven by the higher reliability and
efficiency of the KM design.
