9 FLASH
Philco Reversed Line Polarity or Ground Fault

Furnace will not start; LED status light flashes nine times repeatedly.

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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, Open equipment ground, Shared neutral issues on branch circuit, Faulty control board sensing circuit

How to Fix / Troubleshooting

Electrical safety warning: Working inside the electrical compartment can expose you to lethal voltage. If you are not experienced with electrical work, contact a licensed electrician or HVAC technician.

Basic homeowner checks:

  • 1. Inspect power cord or disconnect: Ensure the furnace is connected to a properly wired outlet or disconnect. Look for obvious damage to the cord or wiring.
  • 2. Check service switch: Verify the furnace service switch is on and not loose or damaged.
  • 3. Do not rewire polarity yourself unless qualified: Reversed polarity must be corrected at the breaker panel or junction box by a qualified person.

When to call a professional: A technician or electrician should verify correct line/hot, neutral, and ground connections and ensure the Philco control board is not damaged. If the board has been compromised by miswiring, it may need replacement.

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Repair Difficulty

Professional Required 5/5

Required Part

Ignition Control Board
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