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Hoshizaki KM-250BWF Service Manual

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HOSHIZAKI
CRESCENT CUBER
MODEL
KM-250BAF
KM-250BWF
SERVICE MANUAL
1
NO.:
ISSUED:
July 24, 2000
REVISED:
December 22, 2004
73094

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Summary of Contents for Hoshizaki KM-250BWF

  • Page 1 HOSHIZAKI CRESCENT CUBER MODEL KM-250BAF KM-250BWF SERVICE MANUAL 73094 NO.: ISSUED: July 24, 2000 REVISED: December 22, 2004...
  • Page 2 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. Should the reader have any questions or concerns which have not been satisfactorily addressed, please call or write to the HOSHIZAKI Technical Support Department for assistance.

  • Page 3: Table Of Contents

    This manual should be made available to the technician prior to service or maintenance. I. Specifications ... 5 1. KM-250BAF ... 5 2. KM-250BWF ... 6 II. General Information ... 7 1. Construction ... 7 [a] KM-250BAF ... 7 [b] KM-250BWF ...
  • Page 4 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.

  • Page 5: Specifications

    I. Specifications 1. KM-250BAF...

  • Page 6: Km-250Bwf

    2. KM-250BWF...

  • Page 7: General Information

    II. General Information 1. Construction [a] KM-250BAF...

  • Page 8: [B] Km-250Bwf

    [b] KM-250BWF...

  • Page 9: Controller Board

    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.
  • Page 10 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.
  • Page 11 The green LED’s 1-4 represent the corresponding relays and energize and sequence 5 seconds from initial start-up as follows: Sequence Step LED’s on Length: 1 Minute Fill Cycle LED4 Harvest Cycle LED1, 4, & 2 Freeze Cycle LED1 Reverse Pump Out LED1, 3, &...
  • Page 12 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.

  • Page 13: [C] Sequence

    [c] Sequence 1st Cycle 1. Unit energized and control switch to “ICE” position. Water supply cycle starts. 2. After 1 minute, defrost cycle starts. 5. After the first 5 minutes in freeze cycle. Ready to complete freeze cycle when float switch circuit opens.
  • Page 14 2nd Cycle and after with pump drain IMPORTANT Freeze cycle time is limited to 60 minutes even if float switch does not open. 1. Float switch opens and signals to complete freeze cycle. Drain timer starts counting. 5. After the first 5 minutes in freeze cycle. Ready to complete freeze cycle when float switch circuit opens.

  • Page 15: [D] Controls And Adjustments

    [d] Controls and Adjustments The dip switch is factory-adjusted to the following positions: DIP SWITCH NO. KM-250BAF, BWF OFF OFF 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.
  • Page 16 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.
  • Page 17 3) Drain Timer The drain timer is factory-adjusted, and no adjustment is required. SETTING Dip Switch No. 3 T1: Time to drain the water tank T2: Time to restrain defrost completion 4) Drain Counter Do not adjust the drain counter, or the evaporator may freeze up. The drain counter is factory-adjusted to drain the water tank every 10 cycles, and no adjustment is required.

  • Page 18: [E] Checking The Controller Board

    5) Freeze Timer 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.
  • Page 19 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.

  • Page 20: Technical Information

    III. Technical Information 1. Water Circuit and Refrigerant Circuit [a] KM-250BAF...

  • Page 21: [B] Km-250Bwf

    [b] KM-250BWF...

  • Page 22: Wiring Diagram

    2. Wiring Diagram KM-250BAF, KM-250BWF Note: Pressure Switch - HI KM-250BAF Cut-out Cut-in 284.5 ±21.3 PSIG KM-250BWF +21.3 +21.3 PSIG PSIG 256 ±21.3 PSIG...

  • Page 23: Timing Chart

    3. Timing Chart The pump motor for KM-250B series does not have drain cycle. The icemaker does not complete a defrost cycle in the first 2 or 3 minutes. See “II. 2. [d] Controls and Adjustments.”...
  • Page 24 The pump motor for KM-250B series does not have drain cycle. The icemaker does not complete a defrost cycle in the first 2 or 3 minutes. See “II. 2. [d] Controls and Adjustments.”...

  • Page 25: Performance Data

    4. Performance Data [a] KM-250BAF...

  • Page 26: [B] Km-250Bwf

    [b] KM-250BWF...

  • Page 27: Service Diagnosis

    IV. Service Diagnosis 1. No Ice Production PROBLEM POSSIBLE CAUSE [1] The icemaker a) Power Supply will not start 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...
  • Page 28 PROBLEM POSSIBLE CAUSE l) Controller Board [2] Water a) Float Switch continues to be supplied, and the ice- maker will not b) Controller Board start. [3] Compressor a) Wash Switch will not start or operates b) High Pressure intermittently Control c) Overload Protector d) Starter e) Start Capacitor...
  • Page 29 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.

  • Page 30: Evaporator Is Frozen Up

    2. Evaporator is Frozen Up PROBLEM POSSIBLE CAUSE [1] Freeze cycle a) Float Switch time is too long. 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.

  • Page 31: Low Ice Production

    3. Low Ice Production PROBLEM [1] Freeze cycle a) See chart 1 - [3], and check dirty air filter or condenser, ambient or water time is long. temperature, water pressure or refrigerant charge. b) See chart 2 - [1], and check float switch, water solenoid valve or controller board.

  • Page 32: Removal And Replacement Of Components

    V. Removal and Replacement of Components Ensure all components, fasteners and thumbscrews are securely in place after the equipment is serviced. 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.

  • Page 33: Brazing

    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.

  • Page 34: Removal And Replacement Of Compressor

    3. Removal and Replacement of Compressor 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.

  • Page 35: Removal And Replacement Of Drier

    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.

  • Page 36: Removal And Replacement Of Expansion Valve

    5. Removal and Replacement of Expansion Valve 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.

  • Page 37: Removal And Replacement Of Hot Gas Valve

    6. Removal and Replacement of Hot Gas Valve Always use a copper tube of the same diameter and length when replacing the hot gas lines; otherwise the performance may be reduced. Always install a new drier every time the sealed refrigeration system is opened.

  • Page 38: Removal And Replacement Of Evaporator

    7. Removal and Replacement of Evaporator 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.

  • Page 39: Removal And Replacement Of Water Regulating Valve - Water-Cooled Model Only

    8. Removal and Replacement of Water Regulating Valve - Water-Cooled Model Only 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.

  • Page 40: Adjustment Of Water Regulating Valve - Water-Cooled Model Only

    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.

  • Page 41: Removal And Replacement Of Thermistor

    10. Removal and Replacement of Thermistor 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.

  • Page 42: Removal And Replacement Of Fan Motor - Except Water-Cooled Model

    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.

  • Page 43: Removal And Replacement Of Pump Motor

    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.

  • Page 44: Removal And Replacement Of Float Switch

    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.”...

  • Page 45: Cleaning And Maintenance

    VI. Cleaning and Maintenance 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 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.
  • Page 46 [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.

  • Page 47: Cleaning And Sanitizing Instructions

    [a] Cleaning Solution Dilute 7 fl. oz. (207 ml) of recommended cleaner Hoshizaki “Scale Away" or “LIME-A- WAY" (Economics Laboratory, Inc.) with 1.3 gallons (4.9 l) of warm water. For safety and maximum effectiveness, use the solution immediately after dilution.
  • Page 48 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.

  • Page 49: [C] Sanitizing Solution

    [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. For safety and maximum effectiveness, use the solution immediately after dilution.
  • Page 50 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.

  • Page 51: Maintenance

    3. Maintenance 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 •...

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Km-250baf

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