Furnace runs but cycles on and off frequently; LED status light flashes five times repeatedly.

Critical safety warning: A flame rollout or cracked heat exchanger can leak carbon monoxide. If you see scorch marks around the burner compartment, smell exhaust in the home, or suspect a rollout, shut off the furnace and call a professional immediately. Do not continue to operate the furnace.

Basic homeowner checks (only if no obvious signs of damage):

• 1. Inspect burner compartment: With power off, remove the burner door. Look for soot, scorch marks, or melted wiring near the burners or rollout switches. If present, stop and call a technician.
• 2. Check flame rollout switches: Locate the small manual-reset rollout switches near the burners. If tripped, they may have a small reset button. Only reset once after verifying there is no blockage or visible damage. If they trip again, do not reset—call a professional.
• 3. Observe burner flame (if safe): Restore power and call for heat. Through the sight glass, check that flames are blue and stable, not lifting, rolling out, or yellow-tipped. Abnormal flames require professional diagnosis.
• 4. Do not attempt gas valve repair: If a stuck gas valve is suspected, the entire gas valve assembly must be replaced. This is not a DIY repair.

When to call a professional: Any 5-flash condition should be evaluated by an HVAC technician. They will test the gas valve, rollout switches, flame sensor, and inspect the heat exchanger. Replacement of the gas valve or heat exchanger with Philco-approved components may be required.