Lennox · Furnace

E405 LSOM - compressor open circuit

High severity EL296UHVLennox SL280UHVLennox SL297NV

What the control is telling you

Compressor circuit open (power disconnected, open fuse, etc.).

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

Likely causes

  • Open fuse
  • Disconnect off
  • Open wiring

Test and repair steps

  1. Check outdoor disconnect and fuses.
  2. Check compressor wiring.
  3. Clears after 1 normal compressor cycle.

Settings for these units

Recommended filter size by cabinet width · EL296UHV

Cabinet widthSide returnBottom return
17-1/2 in.16 x 25 x 1 in. (1)16 x 25 x 1 in. (1)
21 in.16 x 25 x 1 in. (1)20 x 25 x 1 in. (1)
24-1/2 in.16 x 25 x 1 in. (2)24 x 25 x 1 in. (1)

Number in brackets is the quantity of filters.

Filters are field supplied and installed outside the furnace; inspect monthly.

Recommended filter size by cabinet width · Lennox SL280UHV

Cabinet widthSide returnBottom return
14-1/2 in.16 x 25 x 1 in. (1)14 x 25 x 1 in. (1)
17-1/2 in.16 x 25 x 1 in. (1)16 x 25 x 1 in. (1)
21 in.16 x 25 x 1 in. (1)20 x 25 x 1 in. (1)
24-1/2 in.16 x 25 x 1 in. (2)24 x 25 x 1 in. (1)

Number in brackets is filter quantity; filters are field supplied.

Never run the unit without a filter installed.

Models that show this code

22 models in EL296UHV, Lennox SL280UHV, Lennox SL297NV

EL296UH045XV36BEL296UH070XV36BEL296UH090XV36CEL296UH090XV48CEL296UH090XV60CEL296UH110XV48CEL296UH110XV60CEL296UH135XV60DSL280UH060NV36ASL280UH070V36ASL280UH080NV48BSL280UH080NV60CSL280UH090V36BSL280UH090V48BSL280UH090V60CSL280UH100NV60CSL280UH110V60CSL280UH135V60DSL297UH040NV36BSL297UH060NV36BSL297UH080NV48CSL297UH080NV60C

Other codes on the same units

  • E401 LSOM - long run or low pressure
  • E402 LSOM - outdoor pressure trip
  • E403 LSOM - compressor short cycling
  • E404 LSOM - locked rotor
  • E406 LSOM - open start circuit
  • E407 LSOM - open run circuit
  • E408 LSOM - welded contactor
  • E409 LSOM - low secondary voltage

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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.

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.