Navien NCB-180 Service Manual page 101

Check method
Fault Possible Causes
No fan operation
Fan action error
Fan motor RPM
Defective rotator
error
98 NCB Service Manual
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
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.
Check method
Version 1.0