9 RED FLASHES
Coleman Reversed Line and Neutral or Ground Fault

Furnace will not start; status LED shows 9 red flashes repeating; no ignition sequence begins.

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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

Line and neutral wires reversed at furnace, Open or missing equipment ground, Shared neutral or bootleg ground, Faulty control board sensing improper polarity

How to Fix / Troubleshooting

Safety first: Turn off power at the breaker before inspecting wiring. If you are not comfortable with electrical work, contact a licensed electrician or HVAC technician.

Steps to check:

  • Inspect power wiring: Remove the electrical junction box cover on the furnace. Verify that the incoming hot (black) wire is connected to the furnace hot lead and the neutral (white) to the neutral lead. Correct any reversed connections.
  • Confirm proper grounding: Ensure the ground wire is securely attached to the furnace chassis and that the outlet or disconnect feeding the furnace is properly grounded.
  • Check for multi-wire branch circuits: If the furnace shares a neutral with other circuits, improper wiring can cause sensing issues. This should be evaluated by an electrician.

Once wiring is corrected, restore power and reset the furnace. If the 9-flash code remains, the control board may be defective and should be tested and replaced by a professional.

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Repair Difficulty

Hard 4/5

Required Part

Integrated Furnace Control Board
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