Ideal furnace shows F8, blower runs but no heat, or intermittent heating with control board error

Safety: Isolate power before touching the control board. Electronic components are static-sensitive.

Steps:

• Power cycle: Turn off the furnace at the breaker for 5 minutes, then restore power and call for heat. Observe if the error clears temporarily.
• Inspect the PCB: Remove the blower door and visually inspect the Ideal control board for burnt areas, swollen capacitors, or loose connectors. Reseat all multi-pin plugs firmly.
• Check for external causes: Verify correct line voltage at the furnace and that neutral and earth connections are tight. Surges or incorrect wiring can damage the board.
• If F8 persists: The control board is likely defective. Replacement and configuration (if required) should be performed by a qualified technician following Ideal’s service instructions.