Navien NCB-180, Service Manual

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4.9.4 Fan Motor
Part Check Point
Function
To provide combustion air into the burner and to purge exhaust flue gas.
To maintain the gas input with a long vent run, the fan operates with APS for ideal combustion.
Failure Event
1. Fan speed failure: the fan RPM is around 0 RPM.
2. The fan assembly screw is loose and/or the fan is disassembled.
3. Disconnected or defective fan connection terminal assembly.
Effects
1. Unstable combustion condition.
2. Unit vibrating and noise.
3. The boiler is not operating properly.
Error Code
E109, E110
Diagnostic
1. Visual inspection: check the fan connection wire and/or the fan mounting location.
2. Voltage check: Check range of voltage shown below.
Color/Number of wires

Black-Red: DC 127V~184 V

Black-Yellow: DC 15 V

Black-Orange: DC 0~7.5 V

Black-White: 0 ~ 7,000 RPM