C7
Worcester
Fan Not Running
Boiler displays C7, indicating a fan not running or fan speed too low, no ignition.
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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
Seized Worcester fan, no power to fan from PCB, blocked flue causing overload, wiring harness fault
How to Fix / Troubleshooting
Safety first: Isolate power. Do not attempt to spin the fan with power applied.
Homeowner checks:
- Inspect the external flue terminal for obstructions.
- Reset the boiler once; if C7 returns and you do not hear the fan, call an engineer.
Engineer checks:
- Check for 230V (or specified) supply at the fan terminals when a heat demand is present.
- Inspect the fan impeller for debris and check for free rotation by hand (with power off).
- Test continuity of the fan windings; replace the fan if open circuit or mechanically seized.
- Verify flue is correctly installed and not blocked, preventing fan operation.
Fan replacement is a specialist task due to combustion safety requirements.
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Repair Difficulty
Professional Required
5/5
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