73094 NO.
IMPORTANT Only qualified service technicians should attempt to service or maintain this icemaker. No such service or maintenance should be undertaken until the technician has thoroughly read this Service Manual. HOSHIZAKI provides this manual primarily to assist qualified service technicians in the service and maintenance of the icemaker.
Please review this manual. It should be read carefully before the icemaker is serviced or maintenance operations performed. Only qualified service technicians should service and maintain the icemaker. This manual should be made available to the technician prior to service or maintenance. CONTENTS I. Specifications .................................................................................................................... 5 1. KM-250BAF ...............................................................
11. Removal and Replacement of Fan Motor - Except Water-Cooled Model .................. 42 12. Removal and Replacement of Water Valve ............................................................... 42 13. Removal and Replacement of Pump Motor .............................................................. 43 14. Removal and Replacement of Float Switch.............................................................. 44 15. Removal and Replacement of Spray Tubes....................................................
I. Specifications 1.
2.
II. General Information 1.
[b] KM-250BWF 8
2. Controller Board [a] Solid-State Control 1) A HOSHIZAKI exclusive solid-state control is employed in KM-250BAF and KM-250BWF Crescent Cubers. 2) A printed circuit board (hereafter called “controller board”) includes a stable and high quality control system. 3) All models are pretested and factory-adjusted. [b] Controller Board CAUTION 1. Fragile, handle very carefully. 2. A controller board contains integrated circuits, which are susceptible to failure due to static discharge.
2) Defrost Timer The defrost cycle starts when the float switch opens and completes the freeze cycle. But the defrost timer does not start counting until the thermistor senses 48°F at the evaporator outlet. The period from the end of the freeze cycle up to the point of the thermistor's sensing varies depending on the ambient and water temperatures. 3) High Temperature Safety - 127 ± 7°F The temperature of the suction line in the refrigerant circuit is limited by the high temperature safety.
The green LED’s 1-4 represent the corresponding relays and energize and sequence 5 seconds from initial start-up as follows: Sequence Step 1 Minute Fill Cycle Harvest Cycle Freeze Cycle Reverse Pump Out LED’s on Length: LED4 LED1, 4, & 2 LED1 LED1, 3, & 2 Min. Max. 2 min. 5 min. 10 sec. 20 min. 60 min. 20 sec. Avg. 60 sec. 3-5 min. 30-35 min. Factory set. {LED 1 – Comp; LED 2 - HGV/CFM; LED 3 – PM; LED 4 - WV} The built in safeties shut down the unit and have alarms as follows: 1 beep every 3 sec.
to the K1 connector. If there is a white wire, place the switch in the C position. If this switch is placed in the wrong position, either the compressor contactor will remain energized with the control switch OFF, or the unit will not start. The dip switches should be adjusted per the adjustment chart published in the Tech Specs book. 7 & 8 must remain in the OFF position.
[c] Sequence 1st Cycle 3. Thermistor reads 48° F. Defrost timer starts counting. 1. Unit energized and control switch to “ICE” position. Water supply cycle starts. 2. After 1 minute, defrost cycle starts. IMPORTANT Water valve opening is limited to 6 minutes. & 4. Defrost timer stops counting. Defrost cycle is completed and freeze cycle starts. 5. After the first 5 minutes in freeze cycle. Ready to complete freeze cycle when float switch circuit opens. IMPORTANT 1.
2nd Cycle and after with pump drain IMPORTANT Freeze cycle time is limited to 60 minutes even if float switch does not open. 2. Drain timer stops counting. Pump drain is completed 1. Float switch opens and signals to complete freeze cycle. Drain timer starts counting. 3. Thermistor reads 48° F. Defrost timer starts counting. IMPORTANT Water valve opening is limited to 6 minutes. 5. After the first 5 minutes in freeze cycle. Ready to complete freeze cycle when float switch circuit opens.
[d] Controls and Adjustments The dip switch is factory-adjusted to the following positions: DIP SWITCH NO. KM-250BAF, BWF 1 2 3 OFF OFF OFF 4 OFF 5 ON 6 ON 7 OFF 8 OFF 9 OFF 10 OFF Switch Nos. 1 and 2: Used for adjustment of the defrost timer. The defrost timer starts counting when the thermistor reads a certain temperature at the evaporator outlet. Switch Nos. 3 and 4: Used for adjustment of the drain timer.
1) Defrost Control A thermistor (semiconductor) is used for a defrost control sensor. The resistance varies depending on the suction line temperatures. The thermistor detects the temperature of the evaporator outlet to start the defrost timer. No adjustment is required. If necessary, check for resistance between thermistor leads, and visually check the thermistor mounting, located on the suction line next to the evaporator outlet. Temperature (°F) 0 10 32 50 70 90 Resistance (kΩ) 14.401 10.613 6.000 3.
3) Drain Timer The drain timer is factory-adjusted, and no adjustment is required. SETTING Dip Switch Dip Switch No. 3 No. 4 OFF ON OFF ON TIME T1 OFF OFF ON ON T2 10 seconds 10 seconds 10 seconds 20 seconds 150 180 120 180 seconds seconds seconds seconds T1: Time to drain the water tank T2: Time to restrain defrost completion 4) Drain Counter CAUTION Do not adjust the drain counter, or the evaporator may freeze up.
5) Freeze Timer CAUTION Adjust to proper specification, or the unit may not operate correctly. Two new dip switches numbered 9 and 10 have been added to the improved “E” board to better prevent possible freeze ups. These settings come factory set to the default setting of 60 min. (OFF, OFF). Check the adjustment chart published in the Tech Specs for proper settings. If the old board does not have these two dip switches, (only 8 instead of 10), leave setting as OFF, OFF. SETTING Dip Switch Dip Switch No.
After the 1 minute ± 5 second water supply cycle and the 2 minute ± 10 second defrost cycle, the unit should start the freeze cycle. (ii) After the above step (i), disconnect the float switch leads from the controller board within the first 5 minutes of the freeze cycle. The unit should go into the defrost cycle after the first 5 minutes ± 20 seconds of the freeze cycle. (iii) Reconnect the float switch connector to the controller board.
III. Technical Information 1.
[b] KM-250BWF 21
2. Wiring Diagram KM-250BAF, KM-250BWF Note: Pressure Switch - HI KM-250BAF Cut-out Cut-in +21.3 467 0 PSIG 284.5 ±21.3 PSIG KM-250BWF +21.3 427 0 PSIG 256 ±21.
3. Timing Chart *1 The pump motor for KM-250B series does not have drain cycle. *2 The icemaker does not complete a defrost cycle in the first 2 or 3 minutes. See “II. 2. [d] Controls and Adjustments.
*1 The pump motor for KM-250B series does not have drain cycle. *2 The icemaker does not complete a defrost cycle in the first 2 or 3 minutes. See “II. 2. [d] Controls and Adjustments.
4.
[b] KM-250BWF 26
IV. Service Diagnosis 1. No Ice Production PROBLEM [1] The icemaker will not start POSSIBLE CAUSE a) Power Supply 1. “OFF” position. 2. Loose connections. 3. Bad contacts. 4. Voltage too high. b) Fuse (Inside Fused Disconnect, if any) c) Control Switch d) Bin Control Thermostat e) High Pressure Control f) Transformer g) Wiring to Controller Board h) Thermistor i) Hot Gas Solenoid Valve j) Water Supply Line k) Water Solenoid 1. Blown out. 1. “OFF” position. 2. Bad contacts. 1.
PROBLEM [2] Water continues to be supplied, and the icemaker will not start. [3] Compressor will not start or operates intermittently POSSIBLE CAUSE l) Controller Board 1. Defective a) Float Switch 1. Connector disconnected. 2. Leads opened or defective switch. 3. Float does not move freely. 1. Defective. b) Controller Board a) Wash Switch b) High Pressure Control c) Overload Protector e) Start Capacitor f) Magnetic Contactor 2. Voltage too low. 3. Refrigerant overcharged or undercharged. 1.
PROBLEM POSSIBLE CAUSE [5] No water a) Water Supply Line comes from spray tubes. water pump b) Water Solenoid will not start, or Valve freeze cycle time is too c) Water System short. d) Pump Motor e) Controller Board [6] Fan motor will a) Fan Motor not start, or is not operating. b) Controller Board [7] All components a) Refrigerant run but no ice is produced. b) Compressor c) Hot Gas Solenoid Valve d) Water Solenoid Valve 1. Water pressure too low and water level in water tank too low. 1.
2. Evaporator is Frozen Up PROBLEM [1] Freeze cycle time is too long. POSSIBLE CAUSE a) Float Switch b) Water Solenoid Valve 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. Valve 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.
3. Low Ice Production PROBLEM [1] Freeze cycle time is long. [2] Harvest cycle time is long POSSIBLE CAUSE REMEDY a) See chart 1 - [3], and check dirty air filter or condenser, ambient or water temperature, water pressure or refrigerant charge. b) See chart 2 - [1], and check float switch, water solenoid valve or controller board. a) See chart 2 - [2], and check controller board, thermistor, evaporator, ambient and/or water temperature, water supply line, or water solenoid valve. 4.
V. Removal and Replacement of Components IMPORTANT Ensure all components, fasteners and thumbscrews are securely in place after the equipment is serviced. IMPORTANT 1. The Polyol Ester (POE) oils used in R-404A units can absorb moisture quickly. Therefore it is important to prevent moisture from entering the system when replacing or servicing parts. 2. Always install a new filter drier every time the sealed refrigeration system is opened. 3.
5) Disconnect the vacuum pump, and attach a refrigerant service cylinder to the low-side line. Remember to loosen the connection, and purge the air from the hose. See the nameplate for the required refrigerant charge. Hoshizaki recommends only virgin refrigerant or reclaimed refrigerant which meets ARI Standard No. 700-88 be used. 6) Open the low-side valve. Do not invert the service cylinder. A liquid charge will damage the compressor. 7) Turn on the icemaker when charging speed gets slow.
3. Removal and Replacement of Compressor IMPORTANT Always install a new drier every time the sealed refrigeration system is opened. Do not replace the drier until after all other repair or replacement has been made. Note: When replacing a compressor with a defective winding, be sure to install the new start capacitor and start relay supplied with the replacement compressor.
15) Evacuate the system, and charge it with refrigerant. See the nameplate for the required refrigerant charge. 16) Connect the terminals, and replace the terminal cover in its correct position. 17) Replace the panels in their correct position. 18) Plug in the icemaker, and turn on the power supply. 4. Removal and Replacement of Drier IMPORTANT Always install a new drier every time the sealed refrigeration system is opened. Do not replace the drier until after all other repair or replacement has been made.
5. Removal and Replacement of Expansion Valve IMPORTANT Sometimes moisture in the refrigerant circuit exceeds the drier capacity and freezes up at the expansion valve. Always install a new drier every time the sealed refrigeration system is opened. Do not replace the drier until after all other repair or replacement has been made. 1) Turn off the power supply, and unplug the icemaker. 2) Remove the panels. 3) Recover the refrigerant and store it in an approved container.
6. Removal and Replacement of Hot Gas Valve CAUTION Always use a copper tube of the same diameter and length when replacing the hot gas lines; otherwise the performance may be reduced. IMPORTANT Always install a new drier every time the sealed refrigeration system is opened. Do not replace the drier until after all other repair or replacement has been made. 1) Turn off the power supply and unplug the icemaker. 2) Remove the panels. 3) Recover the refrigerant and store it in an approved container.
7. Removal and Replacement of Evaporator IMPORTANT Always install a new drier every time the sealed refrigeration system is opened. Do not replace the drier until after all other repairs or replacements have been made. 1) Turn off the power supply, and unplug the icemaker. 2) Remove the panels and the top insulation over the evaporator. 3) Recover the refrigerant and store it in an approved container.
8. Removal and Replacement of Water Regulating Valve - Water-Cooled Model Only IMPORTANT Always install a new drier every time the sealed refrigeration system is opened. Do not replace the drier until after all other repair or replacement has been made. 1) Turn off the power supply, and unplug the icemaker. 2) Close the water supply line shut-off valve. 3) Remove the panels. 4) Recover the refrigerant and store it in an approved container.
9. Adjustment of Water Regulating Valve - Water-Cooled Model Only The water regulating valve, also called “water regulator”, is factory-adjusted. No adjustment is required under normal use. Adjust the water regulator, if necessary, using the following procedures. 1) Attach a pressure gauge to the high-side line of the system or prepare a thermometer to check for the condenser drain temperature.
10. Removal and Replacement of Thermistor CAUTION 1. Fragile, handle very carefully. 2. Always use a recommended sealant (high thermal conductive type), Model KE4560RTV manufactured by Shinetsu Silicone, Part Code 60Y000-11, or Part Code 4A0683-01 or equivalent. 3. Always use a recommended foam insulation (non-absorbent type) or equivalent. 4. Do not shorten or cut the thermistor leads when installing the thermistor. 1) Turn off the power supply, and unplug the icemaker.
12) Replace the control box cover and the panels in their correct positions. 13) Plug in the icemaker, and turn on the power supply. 11. Removal and Replacement of Fan Motor - Except Water-Cooled Model Note: When replacing a fan motor with defective winding, it is recommended that a new capacitor be installed. 1) Turn off the power supply, and unplug the icemaker. 2) Remove the top, front and left side panels. 3) Remove the screws and the fan shroud. 4) Remove the fan blade.
7) Remove the fitting and the gasket. 8) Release the hose clamp, and disconnect the hose. 9) Remove the water valve from the rear panel. 10) Loosen the two screws, and remove the water valve barrier. 11) Secure the water valve barrier to the new water valve. 12) Install the new water valve, and replace the removed parts in the reverse order of which they were removed. 13) Replace the panels in their correct positions. 14) Open the water supply line shut-off valve.
13) Install the new pump motor, and replace the removed parts in the reverse order of which they were removed. 14) Close the bin door. 15) Replace the panels in their correct positions. 16) Plug in the icemaker, and turn on the power supply. 14. Removal and Replacement of Float Switch 1) Go through the steps 1) through 9) in “13. Removal and Replacement of Pump Motor.” 2) Remove the connectors of the float switch. 3) Remove the screw and the float switch bracket.
VI. Cleaning and Maintenance IMPORTANT Ensure all components, fasteners and thumbscrews are securely in place after any maintenance or cleaning is done to the equipment. 1. Preparing the Icemaker for Long Storage WARNING When shutting off the icemaker for an extended time, drain out all water from the water tank and remove the ice from the storage bin. The storage bin should be cleaned and dried.
[2] Remove the water from the potable water supply line: 1) Remove the front panel. (Except water-cooled model) 2) Move the control switch on the control box to the “OFF” position. 3) Wait 3 minutes. 4) Close the potable water supply line shut-off valve and open the potable water supply line drain valve. 5) Allow the line to drain by gravity. 6) Attach compressed air or carbon dioxide supply to the potable water line drain valve. 7) Move the control switch to the “ICE” position.
2. Cleaning and Sanitizing Instructions IMPORTANT Ensure all components, fasteners and thumbscrews are securely in place after any maintenance or cleaning is done to the equipment. WARNING 1. HOSHIZAKI recommends cleaning this unit at least once a year. More frequent cleaning, however, may be required in some existing water conditions. 2. To prevent injury to individuals and damage to the icemaker, do not use ammonia type cleaners. 3.
4) Remove the plug at the bottom of the water tank to drain the tank. See Fig. 4. After draining, replace the plug in its correct position. 5) Pull out the cap at the front of the plastic body 1" or more. See Fig. 5. 6) Pour the cleaning solution into the water tank. 7) Replace the cap in its correct position. Fig. 4 8) Move the control switch to the “WASH” position. Close the door. 9) After 30 minutes, move the control switch to the “OFF” position. 10) Remove the plug to drain the water tank.
[c] Sanitizing Solution Dilute 1 fl. oz. (30 ml or 2 tbs) of 5.25% sodium hypochlorite solution (chlorine bleach) with 2 gallons (7.6 l) of warm water. Using a chlorine test strip or other method, confirm that you have a concentration of about 200 ppm. IMPORTANT For safety and maximum effectiveness, use the solution immediately after dilution. [d] Sanitizing Procedure The sanitizing process will sanitize the icemaker.
14) Move the control switch to the “ICE” position to fill the water tank with water. 15) After 3 minutes, move the control switch to the “OFF” position. 16) Move the control switch to the “WASH” position. 17) After 5 minutes, move the control switch to the “OFF” position. 18) Remove the plug to drain the water tank. After draining, replace the plug in its correct position. 19) Repeat 14) through 18) two times to rinse thoroughly. 20) Flush the storage bin with water.
3. Maintenance IMPORTANT This icemaker must be maintained individually, referring to the instruction manual and labels provided with the icemaker. 1) Stainless Steel Exterior To prevent corrosion, wipe the exterior occasionally with a clean and soft cloth. Use a damp cloth containing a neutral cleaner to wipe off oil or dirt build up. 2) Storage Bin and Scoop • Wash your hands before removing ice. Use the plastic scoop provided. • The storage bin is for ice use only. Do not store anything else in the bin.
