HVACopedia

Lennox · Furnace

E349 No 24 V between R and O

Critical severity EL296UHVLennox SL280UHVLennox SL297NV

What the control is telling you

Non-communicating outdoor unit: R-to-O configuration link (W951) is missing. Critical alert. Dual fuel module required for heat pump use.

Applies to: EL296UHV(X) series furnaces with integrated control 103130-XX only

Likely causes

  • W951 link cut or open without dual fuel setup

Test and repair steps

  1. Check on-board link W951 (R to O).
  2. Restore the link or hard-wire R to O if not a dual-fuel heat pump application.
  3. For heat pump applications, verify a dual fuel module is installed.

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Source: Lennox EL296UHV(X) Unit Information / Service Literature, Table 5 Ignition Control 103130-XX Diagnostic Codes, p.37. 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.