A09
De Dietrich
Fan / Air Flow Fault
Boiler displays A09, no heating or hot water, fan may not start
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Safety Warning
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.
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Possible Causes
Failed fan motor, seized fan bearings, faulty fan speed feedback, wiring fault between fan and PCB
How to Fix / Troubleshooting
Safety: Isolate electrical supply before accessing the fan. Do not run the boiler with the combustion chamber open.
- Listen for fan operation: On a call for heat, the fan should start before ignition. If silent, suspect the fan or its power supply.
- Visual inspection: Remove the front panel and check the fan connector and wiring for burning or loose plugs. Reseat connectors.
- Spin test: With power off, gently try to rotate the fan impeller. If stiff or seized, the fan assembly must be replaced.
- Technician tasks: A professional should test voltage at the fan during start-up and replace the fan or control board as needed.
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Repair Difficulty
Hard
4/5
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