Navien NCB300-28K Service Manual page 74

Testing method
Fault
Fan action error
Fan motor speed error
Possible Causes
1. Check the voltage at the fan.
●
2. Replace the PCB if the voltage is not present. When replacing a PCB, turn
No fan operation
off the boiler and wait for at least 10 sec before proceeding.
3. If the error condition continues after checking these items, replace the fan
motor.
Check the fan motor's wiring connection
1. If fan speed is very low and the power supply is normal, follow the
instructions below to replace the fan.
1) Unplug the boiler's power cable and wait 10 sec for all remaining SMPS
2) Disconnect the fan cable and then re-connect it.
3) Reconnect the power cable and turn on the boiler.
4) Fan Auto Adjusting verifies error conditions for error code E109. If an
Rotation fault
5) If fan speed is low or there is a sensor circuit error, replace the fan.
2. If the error condition continues after checking these items, replace the
PCB.
Testing method
Black + Yellow, DC 340 V
voltage to completely discharge.
E109 error occurs, enter Fan test mode and verify fan speed and the
APS input voltage. (Eg. The display will show H.320 indicating 3,200
rpm)
This condition indicates an imminently hazardous situation which, if
not avoided, may result in minor or moderate injury.
Troubleshooting 73