9 FLASH
Tappan
Incorrect Line Voltage Polarity or Grounding
Furnace will not start; LED flashes 9 times repeatedly; thermostat appears to be calling for heat.
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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
Hot and neutral reversed at furnace power connection, missing equipment ground, shared neutral issues affecting Tappan control board flame sensing
How to Fix / Troubleshooting
Safety: Only work on electrical wiring if you are comfortable and local codes allow. Otherwise, contact an electrician.
Steps:
- Turn off power at the breaker panel. Remove the furnace electrical junction box cover.
- Verify that the incoming hot (usually black) is connected to L1 and the neutral (white) to neutral on the furnace. Correct any reversed connections.
- Ensure the green or bare copper ground wire is securely attached to the furnace chassis ground screw.
- Use a plug-in outlet tester (if furnace is cord-connected) or a multimeter to confirm correct polarity and grounding at the supply.
- Restore power and check if the 9-flash code clears. If polarity and ground are correct but the code persists, the control board may be misreading ground and require replacement.
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Repair Difficulty
Medium
3/5
Required Part
Integrated Furnace Control Board
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