Furnace will not start; inducer motor does not run; LED status light flashes once repeatedly.

Safety first: Turn off electrical power to the furnace at the service switch and shut off the gas at the gas cock before removing panels. If you ever smell strong gas, evacuate and call the gas utility or fire department.

Step-by-step checks:

• 1. Verify thermostat call for heat: Set thermostat to HEAT and raise the setpoint 5–10°F above room temperature. Confirm the thermostat display shows a heat call and that the furnace LED is powered.
• 2. Check gas supply: Ensure the manual gas shutoff valve near the furnace is parallel to the pipe (open). Confirm other gas appliances in the home work. If no gas to any appliance, contact your gas utility.
• 3. Inspect the hot surface ignitor: Remove the burner access panel. Locate the hot surface ignitor (usually mounted at the burner assembly). Look for cracks, white spots, or broken elements. Do not touch the element with bare fingers. If damaged, replace with a Philco-compatible hot surface ignitor rated for your model.
• 4. Clean or replace the flame sensor: Locate the flame sensor rod near the burner. Remove the mounting screw, pull out the rod, and gently clean it with fine steel wool or emery cloth until shiny. Reinstall and tighten the screw.
• 5. Check wiring to ignitor and flame sensor: Inspect harnesses from the ignition control board to the ignitor and flame sensor for burns, loose connections, or corrosion. Reseat connectors firmly.
• 6. Restore power and test: Turn gas and power back on, then call for heat. Watch through the sight glass: inducer should start, then ignitor should glow, then gas valve should click and burners should light. If the ignitor never glows or the unit quickly locks out again, the ignition control board or gas valve may be faulty.

When to call a professional: If you have confirmed gas supply and cleaned/replaced the ignitor and flame sensor but the furnace still locks out, contact an HVAC technician to test the ignition control board, gas valve, and combustion parameters.