Hoshizaki HWR40A(-D), HUR96A(-D), HUR68A(-D), HUR40A(-D), HWR68A(-D) C. Thermistor Check

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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