Sub-Zero UC-24 series Service Manual
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Sub-Zero UC-24 series Service Manual

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T T e e c c h h n n i i c c a a l l
S S e e r r v v i i c c e e M M a a n n u u a a l l
Under Counter
Series
(UC-24)
SUB-ZERO, INC.
2007 ALL RIGHTS RESERVED
JOB AID #7003933
(Revision B - November 2007)

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Summary of Contents for Sub-Zero UC-24 series

  • Page 1 S S e e r r v v i i c c e e M M a a n n u u a a l l Under Counter Series (UC-24) SUB-ZERO, INC. 2007 ALL RIGHTS RESERVED JOB AID #7003933 (Revision B - November 2007)
  • Page 2 Electronic Control System Under Counter (UC-24) Series ELECTRONIC CONTROL SYSTEM INFORMATION #7003933 - Revision B - November, 2007...
  • Page 3 Electronic Control System Under Counter (UC-24) Series ELECTRONIC CONTROL SYSTEM OVERVIEW Below is the wiring schematic for the model UC-24C, illustrating the components of the electronic control system. • Manual input operations are performed at the control panel (membrane keypad). •...
  • Page 4 Electronic Control System Under Counter (UC-24) Series MAIN CONTROL BOARD LAYOUT AND SUMMARY TABLE Electrical connection points on the main control board are labeled alphanumerically. These labels correspond with the alphanumeric summary table, located on the wiring diagram. By referencing the summary table, it is possible to identify which components are connected at which points on the main control board.
  • Page 5 Electronic Control System Under Counter (UC-24) Series CONTROL PANEL LAYOUT NOTES: • The LCD in these units is not back lit. • Though there is a Bell icon on the LCD, there is no alarm system in the Under Counter Series. The Bell icon will only be observed during Diagnostic Mode, Manual Component Activation Mode and as a Temperature Log Event Indicator.
  • Page 6 Electronic Control System Under Counter (UC-24) Series Sekil 3-6. Cihazin çalistirilmasi ve durdurulmasi için POWER tusu kullanilir. Adjusting Set-Point (Temperature Adjustments) To adjust set-points, press WARMER or COLDER keys on control panel in multiple key strokes until the desired set- point is achieved.
  • Page 7 Electronic Control System Under Counter (UC-24) Series UNIQUE ELECTRONIC CONTROL INPUT OPERATIONS The following pages describe unique input operations that a customer typically would not perform every day. The input operations described here are Temperature Unit Selection Mode, Sabbath Mode and Showroom Mode. Temperature Units Selection (Selecting Fahrenheit or Celsius Display - UC-24C Only) NOTE: For Temperature Unit Selection in the models UC-24R, UC-24RO and UC-24B, see next page.
  • Page 8 Electronic Control System Under Counter (UC-24) Series Temperature Units Selection (Selecting Fahrenheit or Celsius Display - UC-24B, UC-24R, UC-24RO Only) NOTE: For Temperature Unit Selection in the model UC-24C, see previous page. The electronic control is initially set to display temperature in Fahrenheit (°F) units of measure. Units of measure can be converted from °F to °C (Celsius), and/or back again.
  • Page 9 Electronic Control System Under Counter (UC-24) Series Sabbath Mode Sabbath Mode was incorporated into the electronic control system for the observance of certain religious days. Initiating Sabbath Mode disables the LCD and lighting system. To initiate Sabbath Mode, the unit must first be switched OFF using the POWER key (See Figure 3-12), then press and hold the POWER key for approximately ten (10) seconds, until the LCD and lights switch OFF (See Figure 3- 13).
  • Page 10 Electronic Control System Under Counter (UC-24) Series Showroom Mode Showroom Mode was incorporated into the electronic control system so these appliances could be displayed in a showroom setting. When in Showroom Mode, all cooling functions are disabled, but the lighting system and LCD remain active.
  • Page 11 Electronic Control System Under Counter (UC-24) Series FUNCTIONS OF ELECTRONIC CONTROL SYSTEM The following few pages explain monitoring, regulating and controlling functions of the electronic control system. Display Zone Temperatures The temperature signals from the thermistors in the refrigerator and freezer compartments are monitored by the microprocessor and then displayed on the LCD.
  • Page 12 Electronic Control System Under Counter (UC-24) Series Regulate Freezer Zone Temperature (UC-24C Only) When the freezer compartment thermistor detects high off-set temperature, calling for cooling, the compressor and condenser fan motor are energized, as well as the evaporator fan motor. (See Figure 3-18) If the door is opened while the evaporator fan is operating, the microprocessor will detect the power signal to the lights and cut power to the fan.
  • Page 13 Electronic Control System Under Counter (UC-24) Series Regulate Refrigerator Zone Temperature (UC-24C Only) When the thermistor in refrigerator compartment reaches high off-set temperature, calling for cooling, the micro- processor sends an 18 Volt pulse signal to the air baffle control to open, regardless of operational state of the com- pressor.
  • Page 14 Electronic Control System Under Counter (UC-24) Series Regulate Refrigerator Zone Temperature (UC-24B, UC-24R, UC-24RO) When the refrigerator compartment thermistor detects high off-set temperature, calling for cooling, the evaporator fan is energized, but the compressor and condenser fan are not allowed to run until the thermistor on the evaporator rises to 38°F (3°C).
  • Page 15 Electronic Control System Under Counter (UC-24) Series Minimize Condensation on Refrigerator Door Glass (UC-24B Only) To help minimize the formation of condensation, or fog, on the door glass of the model UC-24B, the microprocessor detects when the refrigerator door is opened, via the light switch, then when the door closes, the evaporator fan is energized for five (5) minutes, regardless of compressor operational state.
  • Page 16 Electronic Control System Under Counter (UC-24) Series Monitor and Control Freezer “Adaptive Defrost” (UC-24C Only) Initially, the compressor will cycle-run for 12 hours, after which the microprocessor sends a signal to the defrost relay on the control board to close. This supplies power to the defrost heater. At the same time the compressor, con- denser fan and evaporator fan are switched off.
  • Page 17 Electronic Control System Under Counter (UC-24) Series Monitor and Control Refrigerator Fan-Assisted, Off-Cycle Defrost (UC-24B, UC-24R, UC-24RO) Temperature signals from the compartment and evaporator thermistor’s are observed by the microprocessor. During off cycle defrost, if a refrigerator compartment temperature reaches high offset (calling for cooling) before evaporator temperature rises to 38°F (3°C), no power will be supplied to the compressor.
  • Page 18 Electronic Control System Under Counter (UC-24) Series Monitor Compressor Run Duration, Displays If Service is Needed The microprocessor observes the state of the compressor relay to determine the length of compressor run time (See Figure 3-24). If the compressor runs 100% (Freezer = 6 hours, Refrigerator = 4 hours), an error code is logged (EC 40, or EC 50, respectively), and defrost will be initiated, but SERVICE will not flash.
  • Page 19 Electronic Control System Under Counter (UC-24) Series POSSIBLE ERROR INDICATORS The diagrams on this page illustration what a customers may see on the LCD if a problem/error exists with the unit. NOTE: Error code must be cleared from memory after problems are corrected, otherwise a non-flashing “SERVICE” will display constant on the LCD.
  • Page 20 Electronic Control System Under Counter (UC-24) Series ELECTRONIC CONTROL TROUBLESHOOTING INPUT OPERATIONS The following few pages explain troubleshooting input operations performed at the control panel. The input opera- tions described are Diagnostic Mode, Manual Component Activation Mode and Temperature Log Recall. Diagnostic Mode (a.k.a.
  • Page 21 Electronic Control System Under Counter (UC-24) Series Diagnostic Mode Indicators If “EE” is observed in left display area during Diagnostic Mode, the thermistor in that location is open or shorted, or there is a break in that thermistor’s wiring (See Figure 3-35). Figure 3-35.
  • Page 22 Electronic Control System Under Counter (UC-24) Series Clearing Non-Flashing “SERVICE” and Error Codes If Error Codes are observed in Diagnostic Mode, a non-flashing SERVICE icon will appear on the LCD when Diagnostic Mode ends, indicating error codes are still stored (See Figure 3-38). To clear a non-flashing SERVICE icon and the error codes, the problem must be corrected and the unit must be ON, then: •...
  • Page 23 Electronic Control System Under Counter (UC-24) Series Manual Component Activation Mode Manual Component Activation Mode energizes the cooling system for five (5) minutes, allowing a Service Technician to check for proper voltage readings at activated components without having to wait for the zone to call for cooling. To initiate Manual Component Activation Mode the unit must be ON, then press and hold the desired COLDER key and the POWER key for ten (10) seconds (See Figures 3-41 and 3-42).
  • Page 24 Electronic Control System Under Counter (UC-24) Series Temperature Log Recall Mode The electronic control system is equipped with a temperature history data storage system. This system logs/stores the average temperature of each individual thermistor every two hours, along with any event indicators (explained later in this section), that may have occurred.
  • Page 25 Electronic Control System Under Counter (UC-24) Series Initiate Temperature Log Recall Mode To View Compartment and Evaporator Temperature History: To view compartment and/or evaporator temperature history, begin with the unit ON and in Diagnostic Mode (See Figure 3- 47). While in Diagnostic Mode, toggle through the readings until the desired thermistor temperature is displayed on the LCD (See Figure 3-48).
  • Page 26 Electronic Control System Under Counter (UC-24) Series Temperature Log Event Indicators The diagrams below illustrate possible event indicators that may be observed while in Temperature Log Recall Mode. (See Figures 3-53 through 3-55 and Temperature Log Index Chart on next page) Figure 3-53.
  • Page 27 Electronic Control System Under Counter (UC-24) Series iLK KEZ TAKILAN ELEKTRONIK KARTLAR iÇiN KULLANILAN KART UYGULAMA PROSEDÜRÜ Sekil 3-56. “ - - ” Çift kisa çizgi görünür = Model kodu girilmeye hazirdir. Sekil 3-57. WARMER ya da COLDER tusuna basarak Model numarasini seçiniz. Sekil 3-58.
  • Page 28 Electronic Control System Under Counter (UC-24) Series EL YARDIMIYLA ÇALISMA SEKLi DEGiSTiRME YÖNTEMi (Daha önceden elektrik enerjisi girmis olan-kullanilmis kartlar için uygulanir) Sekil 3-60. Ekran görüntüsü degisinceye kadar COLDER ve POWER dügmelerine basili tutunuz. Press and hold for 15 seconds Sekil 3-61.
  • Page 29 Electronic Control System Under Counter (UC-24) Series DIS MÜDAHALE iLE DEFROST YAPTIRMA iSLEMi (YALNIZ UC-24C) With unit ON, press and hold for 5 seconds Sekil 3-65. Frezer bölümünün COLDER-WARMER ve cihazin POWER tusuna ayni anda 5 Saniye boyunca basili tutun 3-30 #7003933 - Revision B - November, 2007...
  • Page 30 Icemaker Information Under Counter (UC-24) Series ICEMAKER INFORMATION #7003933 - Revision B - November, 2007...
  • Page 31 Icemaker Information Under Counter (UC-24) Series MODULAR ICEMAKER The model UC-24C utilizes a “modular icemaker.” The icemaker operation is not complex, however, an understand- ing of its cycle of operation is necessary in order for a serviceman to make a proper diagnosis. Modular Icemaker Operation When the icemaker thermostat has sensed temperatures of 17°F, the thermostat closes.
  • Page 32 Icemaker Information Under Counter (UC-24) Series Additional Icemaker Operation Notes NOTES: • There is no “ICE” key on the control panel of the UC-24C. However, you may see the ICE icon appear during Diagnostic Mode because the LCD is common with other models. •...
  • Page 33 Icemaker Information Under Counter (UC-24) Series MODULAR ICEMAKER TEST PROCEDURES Perform the following tests if the icemaker is thought to be defective. See Figure 6-3 for icemaker test port loca- tions. Test 1 through 5 are performed with power supplied to the icemaker, so read the “WARNING” below and the “additional Ice Production Notes”...
  • Page 34 Icemaker Information Under Counter (UC-24) Series WATER FILL ADJUSTMENT The water valve should energize for approximately 7.5 seconds. This should supply 140cc. of water to the ice- maker, or approximately 4.75 oz. If this is not the case, the fill amount can be adjusted with the water fill adjust- ment screw.

  • Page 35: Troubleshooting

    Troubleshooting Guides Under Counter (UC-24) Series TROUBLESHOOTING GUIDES #7003933 - Revision B - November, 2007...
  • Page 36 • The Error Code Table and the Error Code Troubleshooting Guide. • The General Troubleshooting Guide, which covers all problems that a UC-24 Series unit may experience. • The Membrane Switch/Ribbon Cable Test Procedures, used to determine if a control panel assembly is defective.
  • Page 37 Troubleshooting Guides Under Counter (UC-24) Series ERROR CODE TROUBLESHOOTING GUIDE TEST / ACTION A. If “EE” for refrigerator compartment was displayed and “SERVICE” flashing, check the following: Thermistor electrical connections and continuity from thermistor to J5 on control board. Reconnect / repair. Resistance of thermistor - 30,000 to 33,000 ohms at 32°F (0°C).
  • Page 38 Troubleshooting Guides Under Counter (UC-24) Series ERROR CODE TROUBLESHOOTING GUIDE TEST / ACTION A. With cold evap. (< 10°F / -12°C), initiate Manual Defrost, then initiate Diagnostic Mode (press POWER key every 20 seconds to keep in Diagnostic Mode) and observe evap. temp. If temperature exceeds 45°F (7°C) and defrost lasts longer then 5 minutes, error code is false.
  • Page 39 Troubleshooting Guides Under Counter (UC-24) Series ERROR CODE TROUBLESHOOTING GUIDE TEST / ACTION A. If Error Code 07, 20, 21, 22, 23, or 24 is also displayed during Diagnostic Mode, see Test/Actions under that code. B. Check for obstructions to freezer door closing. Remove obstruction. C.
  • Page 40 Troubleshooting Guides Under Counter (UC-24) Series HOW TO USE THE GENERAL TROUBLESHOOTING GUIDE • The table on page 8-7 indicate how the General Trouble Shooting Guide is arranged. • Identify the description of the problem that the unit is experiencing from the table. •...

  • Page 41: Table Of Contents

    Troubleshooting Guides Under Counter (UC-24) Series GENERAL TROUBLESHOOTING GUIDE TABLE OF CONTENTS Page # “EE” Displayed in place of Freezer Temperature with “SERVICE” Flashing ............ 8-8 “EE” Displayed in place of Refrigerator Temperature with “SERVICE” Flashing ..........8-8 Warm or Normal Temperatures Displayed with “SERVICE” Alone Flashing ............ 8-8 Warm or Normal Temperatures Displayed with non-flashing “SERVICE”...

  • Page 42: Ee" Displayed In Place Of Freezer Temperature With "Service" Flashing

    Troubleshooting Guides Under Counter (UC-24) Series PROBLEM POSSIBLE CAUSE TEST / ACTION A. “EE” Displayed in place of Freezer Compartment Thermistor Check freezer compartment thermistor elec- Freezer Temperature with Disconnected, Shorted, or misread trical connections from thermistor to control “SERVICE” Flashing board.
  • Page 43 Troubleshooting Guides Under Counter (UC-24) Series PROBLEM POSSIBLE CAUSE TEST / ACTION (Continued) Evaporator Fan Fault F. Warm Refrigerator a. Fan blade obstructed or out of position a. Move obstruction or reposition blade. Temperatures, “SERVICE” b. Evaporator fan motor disconnected b.
  • Page 44 Troubleshooting Guides Under Counter (UC-24) Series PROBLEM POSSIBLE CAUSE TEST / ACTION H. Warm Freezer Temperatures, No Power to Unit Check power to unit, plug unit in or switch “SERVICE” not displayed or supply circuit breaker ON. Flashing Unit Switched OFF Check for “OFF”...

  • Page 45: Warm Freezer Temperatures, "Service" Not Displayed Or Flashing

    Troubleshooting Guides Under Counter (UC-24) Series PROBLEM POSSIBLE CAUSE TEST / ACTION (Continued) Evaporator Heavily Frosted H. Warm Freezer Temperatures, a. Door ajar a. See Door Ajar above. “SERVICE” not displayed or b. Evaporator fan fault b. See Evaporator Fan Fault above. Flashing c.

  • Page 46: No Ice

    Troubleshooting Guides Under Counter (UC-24) Series PROBLEM POSSIBLE CAUSE TEST / ACTION K. No Ice No Water Supply to Unit Connect/turn on water supply. Unit Has Not Run Long Enough Freezer must be 17°F (-8°C) for icemaker to operate, approximately 24 hours after unit installation.

  • Page 47: Icemaker Produces Too Much Ice

    Troubleshooting Guides Under Counter (UC-24) Series PROBLEM POSSIBLE CAUSE TEST / ACTION L. Icemaker produces Too Ice Level Arm/Linkage Bent or Broken Inspect ice level / shut-off arm. Replace much ice defective parts. Icemaker Faulty With ice level arm in UP/OFF position, manually start icemaker with jumper between ports “T”...

  • Page 48: No Lights

    Troubleshooting Guides Under Counter (UC-24) Series PROBLEM POSSIBLE CAUSE TEST / ACTION Q. No Lights No power to unit Check power to unit, plug unit in or switch supply circuit breaker ON. Unit switched OFF Switch unit ON, press POWER key. Unit in Sabbath Mode Exit Sabbath Mode.

  • Page 49: Sealed System Diagnostics Tables

    Troubleshooting Guides Under Counter (UC-24) Series SEALED SYSTEM DIAGNOSTICS TABLES NORMAL OPERATING PRESSURES TABLE NOTES: • Only enter the sealed system to check pressures if the Error Code Troubleshooting Guide and General Troubleshooting Guide could not pinpoint the cause of the temperature problem. •...
  • Page 50 Troubleshooting Guides Under Counter (UC-24) Series EVAPORATOR TEMPERATURE / SEALED SYSTEM LOW-SIDE PRESSURE CORRELATION Temperature Pressure -30°F (-34°C) 10” Vac -25°F (-32°C) 7” Vac NOTE: The temperature/pressure table at right is for refer- -20°F (-29°C) 4” Vac ence only. A unit's temperature/pressure correlation may -15°F (-26°C) 0”...
  • Page 51 Troubleshooting Guides Under Counter (UC-24) Series CONTROL PANEL MEMBRANE SWITCH / RIBBON CABLE TEST If integrity of control panel assembly is suspect, perform continuity tests at membrane switch ribbon cable terminal housing. Begin by removing control panel assembly from unit and place it on solid surface, then disconnecting rib- bon cable from control panel PC board.

  • Page 52: Technical Data

    Technical Data Under Counter (UC-24) Series TECHNICAL DATA #7003933 - Revision B - November, 2007...
  • Page 53 Technical Data Under Counter (UC-24) Series Model UC-24B REFRIGERATOR CHARGE (R-134a Refrigerant) 3.75 oz. (0.11 Kg) NOTE: Always check serial tag for exact charge NORMAL OPERATING PRESSURES Low Side 0 - 12 psi to 30 - 42 psi High Side 75 psi to 110 psi COMPRESSOR NOTE: Always check parts price list for possible substitutions.
  • Page 54 Technical Data Under Counter (UC-24) Series Model UC-24C FREEZER CHARGE (R-134a Refrigerant) 4.5 oz. (0.13 Kg) NOTE: Always check serial tag for exact charge NORMAL OPERATING PRESSURES Low Side 5” Vac - 1 psi to 6 - 12 psi High Side 75 psi to 120 psi COMPRESSOR NOTE: Always check parts price list for possible substitutions.
  • Page 55 Technical Data Under Counter (UC-24) Series Model UC-24R / UC-24RO REFRIGERATOR CHARGE (R-134a Refrigerant) 3.75 oz. (0.11 Kg) NOTE: Always check serial tag for exact charge NORMAL OPERATING PRESSURES Low Side 0 - 12 psi to 30 - 42 psi High Side 75 psi to 110 psi COMPRESSOR...

  • Page 56: Wiring Diagrams

    Wire Diagrams & Schematics Under Counter (UC-24) Series WIRING DIAGRAMS AND SCHEMATICS 10-1 #7003933 - Revision B - November, 2007...
  • Page 57 Wire Diagrams & Schematics Under Counter (UC-24) Series P/N 7002956 REV A WIRING DIAGRAM -This wiring information is provided for use by qualified service personnel only. -Disconnect appliance from electrical supply before beginning service. MODEL UC-24C -Be sure all grounding devices are connected when service is complete.
  • Page 58 Wire Diagrams & Schematics Under Counter (UC-24) Series P/N 7002956 REV A WIRING SCHEMATIC -This wiring information is provided for use by qualified service personnel only. -Disconnect appliance from electrical supply before beginning service. -Be sure all grounding devices are connected when MODEL UC-24C service is complete.

  • Page 59: Wiring Diagram

    Wire Diagrams & Schematics Under Counter (UC-24) Series P/N 7002555 REV A WIRING DIAGRAM -This wiring information is provided for use by qualified service personnel only. -Disconnect appliance from electrical supply before beginning service. -Be sure all grounding devices are connected when service is complete. MODEL UC-24B, UC-24R, UC-24RO -Failure to observe the above warnings may result in severe electrical shock.

  • Page 60: Wiring Schematic

    Wire Diagrams & Schematics Under Counter (UC-24) Series P/N 7002555 REV A WIRING SCHEMATIC -This wiring information is provided for use by qualified service personnel only. -Disconnect appliance from electrical supply before beginning service. -Be sure all grounding devices are connected when service is complete. MODEL UC24-B, UC-24R, UC-24RO -Failure to observe the above warnings may result in severe electrical shock.

This manual is also suitable for:

Uc-24 seriesUc-24cUc-24rUc-24roUc-24b

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