Navien NFC-175, Service Manual

Page: 92 / 138

92 NFC Service Manual
Version 1.0
Check method
Fault Possible Causes Check method
Fan action error
No fan operation
1. Check the power supply to the blower.
●
Black + Red, approx. DC 127~184 V
2. Replace the PCB if voltages are abnormal. (When replacing the PCB, turn off
the unit and then wait for at least 10 seconds before proceeding.)
3. If the issue continues despite the checking the items above, replace the fan
motor.
Check if the fan motor wire is disconnected
Fan motor RPM error Defective rotator
1. If RPM is significantly low while the fan is operating and the power supply is
normal. Follow the instructions listed below and replace the fan.
1) Unplug the power cable to the unit and then wait for 10 seconds until the
remaining SMPS voltage completely discharges.
2) Disconnect the fan cable and then re-connect it.
3) Plug the power cable and turn on the unit.
4) Fan Auto Adjusting verifies error conditions for error code E109. If an E109
error occurs, enter the Fan Test Mode and verify fan RPM and APS input
voltage.(Display: ex. H.320 = 3200 RPM)
5) If RPM is low or there is a sensor circuit error, replace the fan. Indicates an
imminent hazardous situation which, if not avoided, may result in minor or
moderate injury.
2. If the issue continues despite checking the items above, replace the PCB.