Furnace shuts down; LED shows 7 flashes. The blower may continue to run.

Safety: Turn off power and gas before removing the burner assembly or gas components.

Steps:

• Clean flame sensor: Remove and gently clean the flame sensor rod with fine steel wool. Reinstall and ensure it is fully in the burner flame.
• Clean burners: Remove the burner assembly if accessible. Use a soft brush or compressed air to remove rust and debris from burner ports. Ensure crossover ports are clear for proper flame carryover.
• Check gas supply: Confirm other gas appliances operate normally. If multiple appliances show issues, contact the gas utility.
• Observe flame: With panels in place and power restored, observe through the sight glass. Flames should be stable, blue, and not lifting or blowing off the burners. Yellow, unstable, or lifting flames indicate gas or combustion issues requiring professional adjustment.

If the flame continues to drop out during operation, a technician should check manifold gas pressure, gas valve operation, and combustion air supply.