HVACopediaLennox · Furnace
1 flash Line voltage polarity reversed
What the control is telling you
The control sees hot and neutral reversed (107163-01: reversed polarity or phasing of 120 V power). Heat will not run; cooling continues.
Applies to: EL195UHNE furnaces with ignition control 103217-03 or 107163-01 (red LED)
Likely causes
- Hot and neutral swapped at the furnace or in the supply circuit
Test and repair steps
- Warning: Turn off power before rewiring.
- Check that line hot (black) lands on L1/LINE and neutral (white) on N; the furnace electronics are polarity sensitive.
- Check the house wiring/receptacle feeding the furnace for reversed polarity.
- Correct the wiring and restore power.
Settings for these units
Filter sizes (filter rack kits) · Lennox EL195UHNE
| Cabinet | Horizontal end rack | Side return rack |
|---|---|---|
| B width (040, 060) | 18 x 25 x 1 (kit 87L96) | 16 x 25 x 1 (kit 44J22) |
| C width (080, 100) | 20 x 25 x 1 (kit 87L97) | 16 x 25 x 1 (kit 44J22) |
Filters are field supplied; check monthly.
100NE60C over 1800 cfm with single side return needs a 20 x 25 x 1 filter via return air base and transition.
Models that show this code
4 models in Lennox EL195UHNE
Other codes on the same units
- 2 flashes Improper earth ground
- 3 flashes Burner failed to light or lost flame
- 4 flashes Low flame signal
- 5 flashes Watchguard - ignition retries/recycles exceeded
- 7 flashes Primary or secondary limit open
- 8 flashes Rollout switch open
- 9 flashes Pressure switch stays open or drops out on a heat call
- 10 flashes Watchguard - pressure switch opened 5 times in one heat demand
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Source: Lennox EL195UHNE Unit Information Corp 1801-L1 (rev 04/2024), Table 4 (103217-03) / Table 5 (107163-01) diagnostic codes, p.8-10; flowchart p.51. Summarized in our own words; check the original manual for your model.
Homeowner looking at this code? See what it means for you and when to call a technician.
For licensed technicians. Gas, electrical and refrigerant work must be done by a qualified, licensed person. Shut off power and gas before servicing, never bypass a safety control, and follow the manufacturer’s manual for the exact model; it and local codes always take priority. HVACopedia is not affiliated with any manufacturer; brand and model names only identify the equipment.