Navien NFC-175, Service Manual

Page: 114 / 138

114 NFC Service Manual
Version 1.0
5.2.30 615Error
Error occurrence conditions and check items
Error Description
E615 error Abnormal signal input by PCB.
Check items
1. Turn the POWER RESET switch OFF then ON (or unplug and replug the power supply.
2. If the system still displays E615, replace the main PCB.
5.2.31 740Error
Error conditions and Check Items
Error Description
E740
Abnormal outdoor sensor
If an error (under 2.2kΩ or over 122.2kΩ) in the outdoor sensor is detected continuously for
3 seconds, The system displays the error message E740 on the front panel. If this occurs, the
boiler changes the control mode from Reset Curve Mode to Normal Mode.
Check items
1. Check the parameter setting (refer to page 43).
2. Check the outdoor sensor.
Is the Outdoor sensor
installed properly?
Is the outdoor thermistor
normal?
Check connecter
(#1 and #2 of CNT3)
Change the Outdoor Reset Control
Mode setting
(refer to page 43).
Replace the outdoor thermistor.
No
No
Yes
Yes