Thermistor Check; Perimeter Heater; Compressor Protector - Hoshizaki REFRIGERATED PREP TABLE WITH RAISED RAIL 73168 Service Manual

E. Thermistor Check
Thermistors (semiconductors) are used for temperature control in the cabinet and
rail areas, defrost termination, and for monitoring condenser temperature (clogged
filter). The resistance varies depending on temperature. No adjustment is required.
If necessary, check for resistance between thermistor leads and visually check the
thermistor mounting.
1) Disconnect the connector for the thermistor in question under the control box and
behind the wire guard.
2) Remove the thermistor. See "IV.H. Removal and Replacement of Thermistors and
Thermostat."
3) Immerse the thermistor 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 6.5 kΩ
for the cabinet, rail, and defrost thermistors and 145 to 175 kΩ for the condenser
thermistor. Replace the thermistor if it exceeds the normal reading.
F. Perimeter Heater
This unit is equipped with a perimeter heater. This prevents the formation of condensate
on the frame of the unit under high humidity conditions. The unit incorporates a
redundant perimeter heater in the event the main perimeter heater should fail.
G. Compressor Protector
When a combined temperature/amperage value is above the limit specified by the
compressor manufacturer, a protector will operate independently, turning off the
compressor. The compressor will restart when this protector has reset.
Note:
1. Compressor protector resets automatically.
2. If the condenser fan is operating and the compressor is off, it is most likely that the
protector has operated.
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