Check Circuit Board; Check Thermistor Sensor(S) - Cornelius I-SERIES Training Manual

3.1 Sensors
The suction line sensor (blue) is a thermistor rated at 2815 ohm ± 5%, at 32° F (0° C). This
sensor controls the ice bridge thickness by measuring the suction line temperature and
sending it to the circuit board. The circuit board controls the compressor.
If the suction line temperature does not drop to 40° F (4.4° C) in 6 minutes, the ice
machine goes into a safety shutdown mode. A manual reset must be performed.
3.2 Check Circuit Board Output
1. Turn ice machine power switch OFF. Disconnect sensor plug from board.
2. Turn power switched ON.
3. Use digital multimeter set for DC voltage. Connect leads of meter across the two
pins of the sensor being checked.
4. Meter should read 4.5–5.0 VDC. If voltage is not correct, replace the circuit
board.
Note: This also applys to the proximity switch

3.3 Check Thermistor Sensor(s)

1. Disconnect the suction line sensor from the control board.
2. Install a special test cord (p/n 164984009) to the controller board.
3. Reinstall the suction line sensor.
4. Set the multimeter for DC-volts and connect it to the special test cord leads.
5. Operate the ice machine in freeze cycle.
6. As the suction line temperature decreases the volt reading should increase.
• If the multimeter reading remains steady and does not increase, it indicates a
shorted sensor. Replace the sensor and check again.
• If the multimeter reading is 4.5 – 5.0 VDC it indicates an open sensor. Replace
the sensor and check again.
© 2001, IMI Cornelius Inc.
I-Series Ice Machine Training Manual
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