continuous/rapid flashes
Reversed 115 VAC polarity
This code typically points to
- Reversed line polarity
- Poor grounding condition
Next checks to confirm
- Verify line/hot-neutral polarity to furnace
- Verify equipment grounding and wiring correctness
Escalation
Furnace fault indication; operation may be inhibited or unreliable until corrected
Reset behavior
Clears once polarity/grounding issue is corrected.
Urgent
Fix now