C7
Junkers
Fan not running
Boiler displays C7; no fan operation detected when there is a heat demand
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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
Open circuit fan motor, Seized fan bearings, No power supply to fan from PCB, Faulty wiring harness
How to Fix / Troubleshooting
Safety: Isolate power and gas. Do not bypass safety devices.
- Reset and observe: After restoring power, call for heat and listen for any attempt of the fan to start.
- Check for obstructions: Ensure nothing is blocking the fan impeller through the air intake (do not insert tools into live equipment).
- Technician checks:
- Measure voltage at the fan connector when the boiler calls for heat.
- Check fan windings for continuity with a multimeter.
- Inspect the harness for broken wires or burnt connectors.
- Replace the fan assembly if open circuit or seized; if no voltage is present, suspect the main PCB.
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Repair Difficulty
Hard
4/5
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