HVACopediaLennox · Air conditioner
E413 High pressure switch strikes lockout
What the control is telling you
High pressure switch opened five times in one cooling demand; the outdoor unit is shut down. S30/S40 thermostat alert code 413 (shown as E413 on the unit control display).
Applies to: Lennox communicating air conditioners incl. variable-capacity inverter units in S30/S40 smart thermostat systems
Likely causes
- Overcharge
- Outdoor fan failure
- Dirty coil or blocked airflow
Test and repair steps
- Check charge using superheat and subcooling.
- Check outdoor fan operation.
- Remove dirt or debris blocking airflow.
- Reset by putting the outdoor control in test mode or cycling low-voltage power.
Settings for these units
- Outdoor unit clearances · Lennox EL16KC1
Save it for the next call
Star this code in the HVACopedia app and keep the whole library on your phone for jobs with no signal.
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.