Navien NFC-175, Service Manual

Page: 96 / 138

96 NFC Service Manual
Version 1.0
Check method
Fault Possible Causes Check method
Defective sensor
Defective temperature
sensor connector
Check if the temperature sensor is open and if the connector is connected
properly.
Temperature sensor
Check the resistance of the temperature sensor. (Defective if it is 30kΩ or higher)
●
Replace the temperature sensor if the resistance value is abnormal. (refer to
page 54).
●
Check the temperature displayed on the front panel. (refer to page 36).
Possible Issues
Defective circulation
pump(external)
Check power supply to the circulation pump(AC 120V)
Defective PCB If the issues continue despite checking the items above, replace the PCB.
<Heat exchanger output temperature sensor / connector>
<Check if Heat exchanger output temperature sensor is open Error type : MΩ Open>