Status LED flashes once repeatedly, furnace will not start heating cycle

Safety first: Turn off electrical power to the Gibson furnace at the service switch and shut off the gas supply before removing panels. Allow the furnace to cool.

Steps to check:

• Verify gas supply: Confirm the manual gas shutoff valve near the furnace is parallel to the pipe (open). If you smell gas, stop and call a licensed technician immediately.
• Inspect the flame sensor: Remove the burner access panel. Locate the flame sensor (thin metal rod in front of a burner). Disconnect the wire, remove the mounting screw, and gently clean the rod with fine steel wool or a Scotch-Brite pad until shiny. Do not sand heavily. Reinstall and reconnect.
• Check the hot surface ignitor: Visually inspect the ignitor for cracks or white spots. If damaged, replace with a Gibson-compatible hot surface ignitor. Do not touch the new ignitor element with bare fingers; handle by the ceramic base.
• Observe ignition sequence: Restore power and call for heat at the thermostat. Watch through the sight glass: inducer starts, ignitor glows, then gas should flow and flame should appear. If ignitor glows but no flame, suspect gas valve or gas supply.
• If code persists: Turn power back off and contact a qualified HVAC technician to test gas pressure and gas valve operation.