E5 code, furnace shuts down on high temperature, blower may run continuously

Safety first: Turn off power to the furnace before removing panels or reaching near the blower or wiring.

• Step 1 – Check air filter: Locate the return air filter (often in the return grille or furnace filter rack). If dirty or clogged, replace with the correct size and airflow rating. Do not operate without a filter.
• Step 2 – Inspect supply and return airflow: Ensure all supply registers and return grilles are open and not blocked by furniture, rugs, or debris.
• Step 3 – Verify blower operation: Call for heat and observe if the blower starts after the burners ignite. If the blower does not start or is weak/noisy, the blower motor or capacitor may be failing.
• Step 4 – Check evaporator coil (if AC installed): Remove the access panel to the Ducane evaporator coil above the furnace. Inspect for heavy dust, pet hair, or ice buildup. A severely clogged coil requires professional cleaning.
• Step 5 – Reset and test: Some high limit switches are manual reset; others are automatic. After correcting airflow issues, restore power and test operation. If E5 returns quickly, the limit switch or blower system needs professional diagnosis.