E311
Heat rate reduced to match indoor blower airflow
This code typically points to
- Restricted airflow causing cutback mode
Next checks to confirm
- Reduce restriction by checking filter and duct system
Escalation
Warning only; Lennox states two-stage controls reduce to first stage, and firing rate is reduced every 60 seconds to match available CFM
Reset behavior
Clears when heat call finishes successfully.
Service Soon
Schedule repair