Hoshizaki RF28A Service Manual Download Page 27 | Manualshive

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h) Control Board Error Alarms (EA and ED)

"EA" is displayed when an EEPROM write error is detected. "ED" is displayed when an
EEPROM veriﬁcation or read error is detected.

Reset Options

Replacing the control board with a functioning replacement control board will eliminate
this error condition.

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Summary of Contents for RF28A

Page 1: ...Hoshizaki A Superior Degree of Reliability www hoshizaki com Models RR28A RR55A RF28A RF55A Commercial Refrigerators Freezers Hoshizaki America Inc Number 73139 Issued 8 31 2006 SERVICE MANUAL ...

Page 2: ...which have not been satisfactorily addressed please call write or send an e mail message to the HOSHIZAKI Technical Support Department for assistance HOSHIZAKI AMERICA INC 618 Highway 74 South Peachtree City GA 30269 Attn HOSHIZAKI Technical Support Department Phone 1 800 233 1940 Technical Service 770 487 2331 Fax 1 800 843 1056 770 487 3360 E mail techsupport hoshizaki com Web Site www hoshizaki...

Page 3: ...st Interval F0 14 b Setpoint Temperature Differential F2 14 c High Temperature Alarm Delay Time F3 15 d Low Temperature Alarm Delay Time F4 15 e Temperature Display F or C F5 16 f Alarm History F6 16 g Compressor Run Time F7 17 h Not in Use F8 17 i High Temperature Shutoff Temperature Setting FA 17 j Not in Use Fb 17 3 Cabinet Temperature Correction calibration factor 18 E Perimeter Frame Heater 1...

Page 4: ...val and Replacement of Capillary Tube Heat Exchanger Suction Line Assembly 37 J Removal and Replacement of Drain Tank Heater 37 K Removal and Replacement of Primary Drain Tank Thermostat 38 L Removal and Replacement of Safety Drain Tank Thermostat 38 M Removal and Replacement of Drain Tank Thermal Fuse 38 N Removal and Replacement of Evaporator 38 O Removal and Replacement of Condenser 39 P Remova...

Page 5: ... Blank B Construction Condenser Fan Control Box Compressor Capillary Tube Condenser Access Valve C Dimensions Door Opening Total Refrigerated Volume ft3 Total Shelf Space ft2 Width Height RR28A RF28A 571 5 1512 0 21 0 11 5 RR55A 571 5 1512 0 46 0 25 9 RF55A 571 5 1512 0 46 2 25 9 Condenser Filter Drier Regulator Box Clogged Filter Thermistor Cabinet Thermistor Defrost Thermal Fuse Defrost Heater D...

Page 6: ...6 1 RR28A RF28A Units mm in ...

Page 7: ...7 2 RR55A RF55A Units mm in ...

Page 8: ...ondenser fan start up Defrost End Defrost thermistor reaches defrost termination temperature refrigerator 68 F 20 C 4 1 kΩ freezer 95 F 35 C 1 2 kΩ or defrost timer reaches 1 hour 1 Defrost heater off 2 Drain tank heater on thermostatic cut off Defrost Start Preprogrammed time interval 1 Compressor off 2 Evaporator fan off 3 Condenser fan off 4 Defrost heater on 1 9A 5 dF displayed Note 1 Cut on c...

Page 9: ...me Heater Defrost Heater 3 min Start Delay Power ON Time 6 hours Defrost Start Adjustable 5 min Drain Delay 5 min Fan Delay Defrost Indicator 1 min Refrig 8 min Freezer Display Delay 3 min Min ON 3 min Min OFF Defrost Termination Temperature 60 min Max Defrost Duration Drain Tank Thermostat Limit Drain Tank Heater Cycles on off if thermostat limit reached in first 5 min Defrost Thermistor Setpoint...

Page 10: ...ent damage to the board 4 Do not ﬁx the electronic devices or parts on the board in the ﬁeld Always replace the whole board assembly if it goes bad 5 Do not short out power supply to test for voltage 6 Keep the thermistor leads clogged ﬁlter sensor leads and pressure switch leads at least 1 5 away from high voltage leads AC 100 volts or more to protect against electrical noise 1 Start Up Delay The...

Page 11: ...utton SW 132 Manual Defrost LED 123 Lit for Negative Values LED 124 Temperature and Alarm Display Front K311 6 pin Relay Wiring Harness K251 5 pin K101 3 pin Transformer 12V K151 10 pin Thermistor Wiring Harness K361 9 pin F101 3 Amp Fuse Relays Chip Revision Board Part Number Board Part Number Rear Thermistor Wiring Harness K151 Relay Wiring Harness K361 black Power orange Drain Tank Heater Relay...

Page 12: ...is manual and on the display panel for safe and efﬁcient operation of the unit Temperature Display Window Manual Defrost Button Setting Buttons Service Button 1 Adjusting the Setpoint Temperature To set the setpoint temperature follow the steps below Note The temperature display window normally displays the cabinet temperature The factory setting is F To change the display to the Celsius scale see...

Page 13: ... revert to the temperature display Code Item Setting and Display Range Default Refrigerator Freezer F0 Defrost Interval 1 to 12 hours in 1 hour increments 6 6 F2 Setpoint Temperature Differential upper and lower 0 to 6 3 F in increments of 9 F upper 0 to 3 5 C in increments of 5 C 0 9 to 6 3 F in increments of 9 F lower 0 5 to 3 5 C in increments of 5 C 3 6 3 6 F 2 0 2 0 C decimal is not displayed...

Page 14: ... its place The change in the defrost setting will take effect immediately The next defrost will take place after the newly set time interval has elapsed Initiating a manual defrost will restart the defrost timer The evaporator temperature must be below the defrost completion temperature for any defrost manual or auto to be initiated b Setpoint Temperature Differential F2 This value should only be ...

Page 15: ...ndow 2 Press the service button to display the current setting default 2 Press the up or down button to increase or decrease the high temperature alarm delay time Note The time can be adjusted between 0 and 180 minutes in 60 minute increments The display corresponds to time as follows Display Detection Time minutes 0 0 1 60 2 120 3 180 3 Press the service button to save the setting 4 Press the MAN...

Page 16: ...tton and the service button for 5 seconds The cabinet temperature will be displayed using the newly saved temperature scale 4 Afﬁx the C label supplied with the unit to the display panel covering F but not the display window f Alarm History F6 To view the alarm history follow the steps below 1 Press and hold both the button and the service button for 5 seconds F0 should appear in the display windo...

Page 17: ...he display ﬂashes and 00 when this unused setting is viewed i High Temperature Shutoff Temperature Setting FA This value should only be changed after consulting with the factory To change the high temperature shutoff temperature setting follow the steps below 1 Press and hold both the button and the service button for 5 seconds F0 should appear in the display window Press the MANUAL DEFROST button...

Page 18: ...e is 1 8 F 1 0 C See the table below for the default values Setting Range Default Refrigerator Freezer Cabinet Temperature Correction calibration factor 9 0 to 9 0 F in 0 9 F increments 5 0 to 5 0 C in 0 5 C increments 18 1 8 F 10 1 0 C 36 3 6 F 20 2 0 C 2 If it is determined through discussion with the factory that the setting needs to be changed press the up or down button to increase or decreas...

Page 19: ...ur Control board has terminated defrost E3 may alternate with dF instead of the temperature E4 High Pressure Alarm Compressor discharge pressure is outside normal operating range Pressure switch has been triggered 5 or more times in 1 hour Condenser ﬁlter may need cleaning Clean ﬁlter if necessary Allow time for pressure switch to react then turn power off and back on again to reset If switch trip...

Page 20: ... Error Code Priority Description ED 1 EEPROM Veriﬁcation or Read Error Alarm EA 2 EEPROM Write Error Alarm E8 3 Defrost Thermistor Malfunction Alarm E9 4 Clogged Filter Thermistor Malfunction Alarm E4 5 High Pressure Alarm E7 6 Clogged Filter Alarm E3 7 Defrost Alarm E1 8 High Temperature Alarm E2 9 Low Temperature Alarm ...

Page 21: ...ter the machine has been turned off and then turned back on the high temperature alarm feature is not active until the cabinet temperature reaches the lower setpoint temperature differential The high temperature alarm feature operates even during defrost Reset Options The alarm will automatically reset once the cabinet temperature reaches the lower setpoint temperature differential Possible Causes...

Page 22: ...ettings and Diagnostics Menu 0 0 1 60 minutes Note The low temperature alarm timer starts once the cabinet temperature drops 9 F 5 C below the setpoint temperature The low temperature alarm feature operates even during defrost Reset Options The alarm will automatically reset once the cabinet temperature reaches the upper setpoint temperature differential Possible Causes Ambient temperature is low ...

Page 23: ...ostat and defrost thermal fuse are backup safeties for the defrost thermistor d High Pressure Alarm E4 In order to protect the compressor if the discharge pressure reaches a preset value outside the normal operating range a switch will temporarily stop the compressor At another preset pressure the compressor will attempt to restart If the switch is triggered 5 or more times in one hour E4 will be ...

Page 24: ...s dirty The condenser fan motor is locked or otherwise not functioning IMPORTANT If this alarm occurs frequently the compressor discharge temperature is consistently too high Note If the unit is turned off and then back on while the alarm code is displayed the alarm may be reset even if the ﬁlter is not yet clean However the alarm will recur once the compressor discharge temperature reaches 136 4 ...

Page 25: ...er power is turned on However a short circuit can be detected immediately by turning on the power while pressing the button In this case E8 will be displayed immediately if a short circuit is detected A short circuit will not be detected during defrost drain or fan delay Reset Options The alarm automatically resets when one of the following conditions is met The input from the defrost thermistor e...

Page 26: ...the sensor is properly connected A short circuit can be detected immediately by turning on the power while pressing the button In this case E9 will be displayed immediately if a short circuit is detected Reset Options The alarm automatically resets when one of the following conditions is met The input from the clogged ﬁlter sensor exceeds the open circuit detection point equivalent to 7 6 F 22 C T...

Page 27: ...A is displayed when an EEPROM write error is detected ED is displayed when an EEPROM veriﬁcation or read error is detected Reset Options Replacing the control board with a functioning replacement control board will eliminate this error condition ...

Page 28: ...layed 2 Determine why pressure switch is activated See 2 d High Pressure Alarm E4 h Thermistor 1 Defective 1 Check and replace i Control Board 1 Defective 1 Replace control board j Compressor Overload 1 Defective Contacts open 1 Replace k Compressor 1 Open windings 1 Check continuity and replace l Relay Condensing Unit 1 Bad contacts 1 Replace 2 Open coil winding 2 Check and replace 2 Compressor w...

Page 29: ...gerant 1 Leak 1 Repair leak and recharge e Fan Motor 1 Defective 1 Check and replace f Air Filter 1 Clogged 1 Clean g Condenser 1 Dirty 1 Clean h Thermistor 1 Defective 1 Check and replace i Control Board 1 Defective 1 Replace j Outside Heat Source 1 Too close to unit 1 Separate unit from heat source k Air Flow 1 Blockage inside interior 1 Remove blockage by removing or redistributing food product...

Page 30: ...ough defrosts occurring per day Operation in humid conditions 1 Factory default is once every 6 hours If coil is frosting too much can shorten defrost interval d Defrost Heaters 1 Defective 1 Replace heaters e Safety Defrost Thermostat 1 Defective turning off heaters prematurely or open 1 Replace safety defrost thermostat 10 Condensate water overﬂow a Cabinet Contents 1 Loading of large volumes of...

Page 31: ...rs b Compressor 1 Problem with mount 1 Properly mount compressor Replace any missing grommets 2 Floodback to compressor 2 Check for signs of ﬂoodback to compressor Evacuate and recharge if necessary 3 Defective 3 Replace c Fan 1 Fan blade loose 1 Adjust and tighten 2 Defective motor 2 Replace d Relay 1 Chattering 1 Replace ...

Page 32: ...abinet Defrost Thermistor T R Curve To check a thermistor s resistance follow the steps below 1 Disconnect the connector for the thermistor in question from the control box 2 Remove the thermistor See IV F Removal and Replacement of Thermistor 3 Immerse the thermistor sensor portion in a glass containing ice and water for 2 or 3 minutes 4 Verify the temperature in the glass then check for resistan...

Page 33: ...rubber hose and gauge manifold to be used for evacuation and refrigerant charge should be exclusively for POE oils 2 Turn on the vacuum pump Never allow the oil in the vacuum pump to ﬂow backward 3 Allow the vacuum pump to pull down to a 29 9 Hg vacuum Evacuating period depends on pump capacity 4 Close the low side valve and high side valve if not already closed on the service manifold 5 Disconnec...

Page 34: ...nplug the unit 2 Remove the panels 3 Recover the refrigerant and store it in an approved container 4 Remove the terminal cover on the compressor and disconnect the compressor wiring Be sure to discharge the start capacitor 5 Remove the discharge process and suction pipes from the old compressor 6 Remove the hold down bolts washers rubber grommets and sleeves 7 Remove the old compressor 8 Unpack th...

Page 35: ...sitions 9 Plug in the unit and turn on the power supply E Removal and Replacement of Thermistors 1 Turn off the power supply and unplug the unit 2 Remove the panels Cabinet Thermistor 3 Remove the screws securing the evaporator shroud Pull the shroud forward and gently lower it 4 Remove the thermistor from the bracket and replace 5 Replace the parts and panels in their proper positions in the reve...

Page 36: ...ns outside of the cabinet 8 Replace the parts and panels in their proper positions in the reverse order of the removal procedure 9 Plug in the unit and turn on the power supply G Removal and Replacement of Safety Defrost Thermostat 1 Turn off the power supply and unplug the unit 2 Remove the panels 3 Remove the screws securing the evaporator shroud Pull the shroud forward and gently lower it 4 Rem...

Page 37: ...ier in position 6 Braze all ﬁttings while purging with nitrogen gas ﬂowing at a pressure of 3 to 4 psig 7 Check for leaks using nitrogen gas 140 psig and soap bubbles 8 Evacuate the system and charge it with refrigerant see the nameplate for the required refrigerant charge 9 Insulate the lines to match the original conﬁguration 10 Replace the panels in their correct positions 11 Plug in the unit a...

Page 38: ...ety drain tank thermostat from the drain tank assembly 5 Replace the thermostat 6 Replace the parts and panels in their proper positions in the reverse order of the removal procedure 7 Plug in the unit and turn on the power supply M Removal and Replacement of Drain Tank Thermal Fuse 1 Turn off the power supply and unplug the unit 2 Remove the panels 3 Remove the drain tank cover 4 Remove the drain...

Page 39: ...le purging with nitrogen gas ﬂowing at a pressure of 3 to 4 psig 14 Check for leaks using nitrogen gas 140 psig and soap bubbles 15 Evacuate the system and charge it with refrigerant See the nameplate for the required refrigerant charge 16 Replace the parts and panels in their proper positions in the reverse order of the removal procedure 17 Plug in the unit and turn on the power supply O Removal ...

Page 40: ...ORTANT When receiving a service call please ask the customer to turn the power off then turn it back on and monitor the condition for awhile Even if the control board malfunctions for some reason it may resume normal operation after the power is turned off once CAUTION 1 Fragile handle very carefully 2 A control board contains integrated circuits which are susceptible to failure due to static disc...

Page 41: ...ox taking care not to damage it 6 Hook all wiring connections back to the control board 7 Replace the regulator box cover and the panels in their proper positions 8 Plug in the unit and turn on the power supply R Removal and Replacement of Fan Motors 1 Turn off the power supply and unplug the unit For the remainder of the procedure see the appropriate section below Condenser Fan Motor 2 Remove the...

Page 42: ...as the previous motor with no slack around the fan motors Make wiring connections outside of the cabinet 6 Replace the parts and panels in their proper positions in the reverse order of the removal procedure 7 Plug in the unit and turn on the power supply S Door Re Hinging For re hinging options please contact the factory ...

Page 43: ...gularly E Air Filter As the air ﬁlter becomes clogged with dirt or dust the unit s performance will be reduced Do not operate the unit with the air ﬁlter removed This will accelerate clogging of the condenser and result in failure Check the ﬁlter at least twice each month If it is dirty use warm water and a neutral cleaner to wash the ﬁlter To avoid damaging the air ﬁlter do not use water hotter t...

Page 44: ...iring Diagrams A RR28A CAUTION Before diagnosing and or servicing the unit conﬁrm that you have the proper wiring diagram by checking against the diagram located inside the front panel Intentionally Left Blank ...

Page 45: ...45 B RR55A CAUTION Before diagnosing and or servicing the unit conﬁrm that you have the proper wiring diagram by checking against the diagram located inside the front panel Intentionally Left Blank ...

Page 46: ...r Fan Relay X3 Defrost Heater Relay X4 Compressor Relay 2 X5 Drain Tank Heater Relay X6 Lamp Evaporator Fan Motor Relay X7 Pressure Switch Circuit Relay X8 Evaporator Shroud Duct Heater Relay Thermostat and Thermal Fuse Open Temps Defrost Thermostat Safety 120 F 49 C Defrost Thermal Fuse 201 F 94 C Drain Tank Thermostat Primary 212 F 100 C Drain Tank Thermostat Safety 176 F 80 C Drain Tank Thermal...

Page 47: ...47 D RF55A CAUTION Before diagnosing and or servicing the unit conﬁrm that you have the proper wiring diagram by checking against the diagram located inside the front panel Intentionally Left Blank ...

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