Furnace LED displays code 33; the unit may run briefly then shut down; the blower may continue to run.

Safety: A rollout condition can be hazardous. If you observe scorch marks or smell strong combustion fumes, immediately shut off the furnace and call a professional.

Steps to check (airflow-related):

• Filter and vents: Replace dirty filters and ensure all vents are open.
• Blower operation: Confirm the blower starts on time and runs at the correct speed. Weak airflow suggests motor or capacitor issues.
• Reset rollout (if tripped and safe): After cooling, press the reset button on any manual-reset rollout switches located near the burners. If they trip again, stop and call a technician.

When to call a pro: A technician should inspect the heat exchanger, flue, and burner alignment, and test or replace limit and rollout switches as needed.