10
Rheem
Reversed Line Polarity or Grounding Issue
Status LED flashes 10 times; furnace may not respond to thermostat
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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
How to Fix / Troubleshooting
High-voltage safety: This involves 120/240V wiring. If you are not comfortable with electrical work, contact a licensed electrician or HVAC technician.
- Verify outlet or disconnect wiring: Use a plug-in outlet tester or multimeter to confirm correct hot, neutral, and ground at the furnace power source.
- Inspect furnace junction box: With power off at the breaker, open the furnace electrical junction box. Confirm black (hot) to hot feed, white (neutral) to neutral, and green/bare to ground.
- Check ground bond: Ensure the furnace cabinet is bonded to the ground wire with a tight screw or clamp.
- Reset control: After correcting wiring, restore power and verify the error clears.
Incorrect polarity can interfere with flame sensing and safety circuits; do not operate the furnace until wiring is corrected.
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Repair Difficulty
Hard
4/5
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