Navien NFC-175, Service Manual

Page: 78 / 138

78 NFC Service Manual
Version 1.0
Failure mode Cause Check method
Ignition failure
Main gas valve
1. Check the primary/secondary power supply to the main gas valve.
●
Check, with a multi-meter, between the RED-YELLOW and WHITE-RED wires to verify
that the input power is DC 22-24V.
2. Replace the PCB if power is not supplied.
3. If power supply is normal, check if the coil is open.
●
Check the resistance.
4. Check if the solenoid valve works properly.
●
Feel or hear a click.
2
3
4
1
PIN No.
Check if the coil is open (Proper resistance range : 100~1,000 Ω)
Check the voltage of the solenoid valve / Red-Yellow, White-Red