HVACopedia

Lennox · Heat pump

E415 High discharge line temperature strikes lockout

High severity

What the control is telling you

Discharge line was above 279 F five times in one demand; unit locked out. S30/S40 thermostat alert code 415 (shown as E415 on the unit control display).

Applies to: Lennox communicating heat pumps incl. variable-capacity inverter units in S30/S40 smart thermostat systems

Likely causes

  • Dirty coil or blocked airflow
  • Incorrect charge

Test and repair steps

  1. Clean the coil and clear airflow.
  2. Check charge with superheat and subcooling.
  3. Fix the cause, then reset by test mode or cycling low-voltage power.

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Source: Lennox Residential Communicating Systems Alert Code Guide (V2) 100017 (3/2023), Table 2 Alert Codes and Troubleshooting, p.30. 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.