Hoshizaki HWR40A(-D), HUR96A(-D), HUR68A(-D), HUR40A(-D), HWR68A(-D) service manual Thermistor Check

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C. Thermistor Check

A thermistor (semiconductor) is used for the cabinet control sensor and defrost termination sensor. The resistance varies depending on temperature. No adjustment is required. If necessary, check for resistance between thermistor leads and visually check the thermistor mounting.

Temperature		Resistance (kΩ)
°F	°C	Cabinet/Defrost Thermistors	Clogged Filter Thermistor
0	-17.8	14.2	-
10	-12.2	10.7	-
32	0.0	6.0	160
50	10.0	3.9	100
70	21.1	2.5	59
90	32.2	1.6	36

Cabinet & Defrost Thermistor T-R Curve Clogged Filter Thermistor T-R Curve

Temperature °F (°C)

Temperature °F (°C)

To check a thermistor's resistance, follow the steps below.

1)Disconnect the connector for the thermistor in question under the control box and behind the wire guard.

2)Remove the thermistor. See "IV.F. Removal and Replacement of Thermistors."

3)Immerse the thermistor sensor portion in a glass or cup containing ice and water for 2 or 3 minutes.

4)Check for a resistance between thermistor leads. Normal reading is from 5 to 6.5kΩ for the cabinet and defrost thermistors and 145 to 175kΩ for the clogged filter sensor. Replace the thermistor if it exceeds the normal reading.

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Contents Superior Degree Reliability Energy Star Contents Page Specifications Nameplate Ratings DimensionsUndercounter Model Names HUR40A, HUF40A Units mm 1a. HUR40A-D, HUF40A-D 2a. HWR40A-D, HWF40A-D HWR40A, HWF40A3a. HUR68A-D, HUF68A-D HUR68A, HUF68A4a. HWR68A-D, HWF68A-D HWR68A, HWF68AHUR96A Units mm 5a. HUR96A-D HWR96A Units mm 6a. HWR96A-D Evaporator Case II. General Information ConstructionSequence of Operation and Timing Charts Refrigerators Continuous Operating ModeSequence of Operation Operating Timing ChartFreezers Continuous Operating Mode Freezers Continuous Defrost End Defrost thermistor reaches defrost Refrigerators Energy Saving Operating ModeEnergy Board Self Check Minute Delay Freezers Energy Saving Operating ModeFreezers Energy Control Board Start-Up DelayThermistor Wiring Harness K151 Relay Wiring Harness K311Rear FrontGaining Access to Settings and Diagnostics Settings and DiagnosticsTemperature Display Switching the Display Between Fahrenheit and Celsius F5Adjusting the Setpoint Temperature Cabinet Temperature Correction calibration factor Later Section Settings and Diagnostics MenuDefrost Interval F0 Defrost Termination Temperature F1Setpoint Temperature Differential F2 Low Temperature Alarm Delay Time F4 High Temperature Alarm Delay Time F3Alarm History F6 Temperature Display Scale F5Operating Modes Compressor Run Time F7Perimeter Frame Heater ContinuousEnergy Saving Alarm Signals Alarm Code Problem III. Service Diagnosis Alarm CodesError Code Priority Description Alarm Display PriorityHigh Temperature Alarm E1 Alarm Details and CountermeasuresReset Options Possible CausesLow Temperature Alarm E2 High Pressure Alarm E4 Defrost Alarm E3Clogged Filter Alarm E7 Defrost Temperature Sensor Malfunction Alarm E8 Clogged Filter Sensor Malfunction Alarm E9 Control Board Error Alarms EA and ED Problem Possible Cause Remedy Diagnosis ChartProblem Possible Cause Remedy Problem Possible Cause Remedy Thermistor Check Service for Refrigerant Lines IV. Removal and Replacement of ComponentsRefrigerant Recovery BrazingEvacuation and Recharge Removal and Replacement of Compressor Removal and Replacement of Refrigeration UnitRemoval and Replacement of Evaporator Page Page Cabinet Thermistor Removal and Replacement of ThermistorsDefrost Thermistor Clogged Filter Thermistor sensorRemoval and Replacement of Defrost Heater Removal and Replacement of Door GasketRemoval and Replacement of Control Board Door Re-Hinging and Drawer Conversion Removal and Replacement of Fan MotorsCondenser Fan Motor Evaporator Fan MotorCleaning Cleaning and Maintenance InstructionsAir Filter MaintenanceShelves Drawers115/60/1 A2. HUR40A-D, HWR40A-D auxiliary code Q6 and later HUF40A-D, HWF40A-D C1. HUR68A, HWR68A auxiliary code Q5 and earlier C2. HUR68A-D, HWR68A-D auxiliary code Q6 and later HUF68A-D, HWF68A-D HUR96A-D, HWR96A-D