Furnace shuts down immediately after ignition attempt; rollout switch trip indicated on diagnostic chart.

Critical safety: A tripped rollout switch can indicate dangerous combustion conditions, including potential carbon monoxide. Do not bypass or repeatedly reset rollout switches.

Steps to check (visual only):

• Inspect around burners: With power off, remove the burner access panel and look for signs of soot, scorch marks, or melted wiring near the burners.
• Check venting: Ensure the flue pipe is intact, properly connected, and not visibly blocked.
• Reset only once (if manual reset type): If your rollout switch has a reset button, you may press it once after correcting any obvious vent blockage. If it trips again, do not reset.

When to call a technician: Any rollout event requires immediate professional inspection of the heat exchanger, burners, and venting system.