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Lennox · Furnace

2 flashes Improper earth ground

Medium severity Lennox EL195UHNE

What the control is telling you

The control does not see a proper earth ground. Heat will not run; cooling continues. A poor ground also shortens ignitor life.

Applies to: EL195UHNE furnaces with ignition control 103217-03 or 107163-01 (red LED)

Likely causes

  • Missing or loose equipment ground
  • Poor ground at the panel

Test and repair steps

  1. Warning: Disconnect power before working on ground connections.
  2. Check the green ground wire at the furnace and back to the panel; tighten connections.
  3. Check ground at the control AC volts between line neutral and the C terminal should be about 0.3 V (2 V max) at idle, 0.75 V (5 V max) with inducer/ignitor on, under 2 V (10 V max) with blower on; line hot to neutral should be 97-132 VAC.
  4. Repair the ground before operating the furnace if readings exceed the maximums.

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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; Table 22, p.45. Summarized in our own words; check the original manual for your model.

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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.