HVACopediaLennox · Furnace
13 flashes Low line voltage
What the control is telling you
Line voltage is too low. Below 70 V the control will not answer a heat call until voltage is above 75 V; cooling continues.
Applies to: EL195UHNE furnaces with ignition control 103217-03 or 107163-01 (red LED)
Likely causes
- Low utility voltage
- Loose connections or undersized wiring
- Generator/inverter supply
Test and repair steps
- Measure line voltage at the control hot to neutral should be 97-132 VAC.
- Check breaker, disconnect and connections for voltage drop under load.
- Correct the supply; heating restarts once voltage is back above 75 V.
Settings for these units
- Filter sizes (filter rack kits) · Lennox EL195UHNE
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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.51-52. Summarized in our own words; check the original manual for your model.
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