A08
Riello
Combustion Air Fan / Pressure Fault
Burner stops with code indicating air pressure or fan fault during operation
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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
Faulty combustion fan motor, Blocked fan wheel or air intake, Defective air pressure switch, Loose fan wiring or capacitor failure
How to Fix / Troubleshooting
Safety: Turn off power and lock out the breaker. Do not place fingers near fan blades.
Steps:
- Inspect fan wheel: Remove burner cover and visually inspect the combustion fan wheel for dirt buildup or foreign objects. Clean with a brush and vacuum.
- Check air intake: Ensure the air intake duct and louvers are clear of dust, insulation, or debris.
- Test fan motor: Try spinning the fan wheel by hand (with power off). It should rotate freely. If stiff or seized, the motor may be failing.
- Verify pressure switch: Inspect tubing to the pressure switch. Replace brittle or cracked tubing. Use a multimeter to confirm the switch closes when the fan runs.
Persistent A08 usually requires motor or pressure switch replacement by a technician.
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Repair Difficulty
Hard
4/5
Required Part
Combustion Fan Motor
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