Status LED flashes code 44 (four short, four long). Furnace may lock out or fail to complete a heating cycle.

Safety first: Overheating can damage equipment and pose a fire risk. Turn off power and gas before inspection.

• Inspect evaporator coil (if A/C installed): Remove the access panel above the furnace and visually inspect the coil for dust and debris. A severely clogged coil restricts airflow and causes limit trips. Clean or have it professionally cleaned.
• Check blower compartment: Ensure there are no obstructions around the blower inlet and that insulation or wiring is not blocking airflow.
• Locate auxiliary limits: These are often mounted on the blower housing or near the secondary heat exchanger. With power off, check continuity. Replace any open limit that does not reset.
• Verify blower speed and filter: Use the correct blower speed tap for heating and ensure the filter is clean and properly sized.