109Error - Navien NCB-180 Service Manual

5.2.9 109Error

Error occurrence conditions and check items
Error
The system checks the RPM signal after the fan starts to run, and displays the error message 109E (cleared
manually) in the following cases:
E109
1. If the RPM remains low or close to 0, the system determines RPM error, and the boiler switches into Lock-
Fan motor RPM
Out (gas valve and ignition transformer locked). (However, the air pressure sensor should be normal.)
error
2. If the RPM signal of low or close to 0, is detected for 3 seconds during combustion, the system stops
combustion, and the boiler switches into Lock-Out. (However, the air volume sensor should be normal.)
1. Check if the fan motor works normally using the component test mode (refer to page 21).
2. Check the power supply to the fan (Black + Red, approx. DC 127~184 V)
3. If RPM is significantly low while the fan works and the power supply is normal, replace the fan motor.
Check items
4. If the fan connector is wet due to any reason including leakage, take corrective action by powering the
unit OFF, then drying the components completely before continuing operation.
5. Check for loose connection of white connector that attaches the fan motor to the PCB.
Does the fan motor have
nominal operation
voltage?
Yes
Is there any voltage from
the fan motor?
Yes
Check fan assembly
Description
NO
Check power and connector
Check the voltage between #4 and #7 CN 8:
127-184V DC (check page 56 for Wiring Diagram)
NO
Check the PCB
Check the voltage between #3 and #4 CN 8:
0-7.5V DC