Furnace displays E07 and blower runs continuously without heat

Safety first: Turn off power before accessing the blower compartment or control board.

• Inspect wiring: Locate the low limit or fan limit switches (often on the blower housing or near the heat exchanger). Check for loose or burned wires and tighten connections.
• Check for obstructions: Ensure nothing is blocking the blower wheel or air passages in the blower compartment.
• Reset manual limits: Some auxiliary limits have a manual reset button. Press gently if present. If the switch immediately trips again, there is an underlying overheating issue.
• Test continuity: With power off, remove one wire from the suspect limit switch and test for continuity across the terminals. An open circuit at room temperature indicates a failed switch.
• When to replace: Replace any open or intermittent limit switch with the correct Napoleon-specified temperature rating. If all limits test good but E07 persists, the control board limit circuit may be faulty and require replacement by a technician.