Noritz Combustion Fan Feedback Error

Boiler displays error 91 and may not maintain stable operation.

This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.

If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.

Possible Causes

Faulty fan speed sensor, Loose fan connector, Control board feedback circuit issue

Safety: Turn OFF power before accessing the fan and control board.

1. Inspect fan connector: Locate the combustion fan connector and ensure it is fully seated and free of corrosion.
2. Check wiring: Look for damaged or pinched wires between the fan and control board.
3. Reset unit: Restore power and attempt to restart. If error 91 returns, the fan assembly or control board may be defective.
4. Professional replacement: A technician should test fan feedback signals and replace the combustion fan motor or control board as needed.

Hard 4/5

Combustion Fan Motor Assembly

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