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Lennox · Air conditioner

71514 System low on refrigerant charge

Medium severity

What the control is telling you

Average subcooling outside expected range for outdoor temperature and compressor Hz. (S40 system diagnostics) S30/S40 thermostat alert code 71514.

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

Likely causes

  • See description

Test and repair steps

  1. Leak check and add refrigerant to correct charge.
  2. Clears automatically once fixed.

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Source: Lennox Residential Communicating Systems Alert Code Guide (V2) 100017 (3/2023), Table 2 Alert Codes and Troubleshooting, p.50. 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.