Error Code C
Info

Lennox EL296UHV Error Code C: Cooling Stage

TL;DR
Your Lennox EL296UHV is operating in cooling mode. The display shows the cooling stage and airflow setting — this is normal.
Disclaimer
This article is for informational purposes only and does not guarantee the accuracy or completeness of the information provided. Always turn off power and gas supply before attempting any repairs. If you smell gas, leave immediately and call your gas company. Consult a licensed HVAC technician for diagnosis and repair. Any actions taken based on this information are at your own risk.

What Does Code C Mean?

The letter C on the Lennox EL296UHV seven-segment display indicates that the system is currently operating in cooling mode. The display cycles through the cooling stage number (1 or 2), the current CFM airflow setting, and then repeats. The C blinks at 1 second on, 0.5 second off.

This is normal operation when your thermostat has called for cooling. In a two-stage cooling system, stage 1 provides lower-capacity cooling for milder days, while stage 2 delivers full cooling capacity for hotter conditions. The furnace blower runs at the appropriate speed for each stage as configured during installation.

No action is needed. The system will continue cooling until the thermostat is satisfied, then return to idle mode. If you feel the cooling is inadequate despite the system running, the issue may be with the outdoor air conditioning unit or refrigerant charge rather than the furnace.

When to Call a Professional

Contact a licensed HVAC technician if:

Sources

  1. Lennox EL296UHV Unit Information (Corp. 1125-L5)

✓ Verified against manufacturer service manual — March 2026