Furnace does not start; LED status light flashes seven times repeatedly.

Safety first: Disconnect power before touching wiring or burner components.

Step-by-step checks:

• 1. Verify flame sensor position: Ensure the flame sensor rod is fully in the burner flame path when burners are lit. If bent away, gently reposition it.
• 2. Clean burner ground connections: Locate the ground wire from the burner rack to the furnace chassis. Remove and clean the contact surfaces with emery cloth, then reattach tightly.
• 3. Clean burner surfaces: Lightly brush rust and scale from the burner surfaces to improve flame contact and grounding.
• 4. Inspect wiring harness: Check the flame sensor wire from the sensor to the control board for damage or loose connections. Reseat the connector at the board.

When to call a professional: If proper grounding and sensor placement do not resolve the issue, the ignition control board may not be reading flame current correctly and should be tested and replaced by a technician with a Philco-compatible control.