Furnace ignites but produces yellow, lazy, or lifting flames.

Warning: Yellow flames can indicate carbon monoxide production. If you suspect unsafe combustion, shut down the furnace and contact a professional immediately.

• Step 1 – Visual inspection: Observe flames through the burner view port. They should be mostly blue with small yellow tips.
• Step 2 – Clean burners: With power and gas off, remove and clean burners. Reinstall correctly.
• Step 3 – Check combustion air: Ensure combustion air openings or intake piping are not blocked.
• Step 4 – Professional combustion test: Have a licensed technician perform a combustion analysis and adjust gas pressure or correct venting issues as needed.