Furnace control indicates rollout switch open; burners shut down immediately after ignition attempt.

Critical safety warning: A tripped rollout switch can indicate dangerous combustion problems and potential carbon monoxide risk. Turn off power and gas and do not operate the furnace until inspected.

Steps (visual checks only for homeowners):

• Locate the CTC flame rollout switches near the burner openings. Some are manual reset; others are one-time use.
• If a manual reset rollout has tripped, you may see a small reset button. Do not repeatedly reset without finding the cause.
• Inspect the burner compartment for heavy soot, melted wiring, or signs of flame escaping the burner area. If present, stop and call a professional immediately.
• Check that the flue pipe is intact and not collapsed or disconnected.

Professional-only repairs: Cleaning or replacing burners, inspecting and replacing a cracked heat exchanger, and replacing rollout switches must be done by a licensed HVAC technician using OEM CTC rollout switches and parts.