Display shows Er11 and furnace shuts down; may occur during normal operation.

Safety first: Turn off and unplug the furnace. Allow it to cool before working near the blower or wiring.

Steps:

• 1. Listen for blower operation: During a heat call, the convection blower should start after the furnace warms up. If it never starts or is very weak, proceed with checks.
• 2. Access the blower: Remove the access panel to reach the convection blower assembly mounted on the hot air plenum or cabinet.
• 3. Inspect the blower wheel: Check for dust, pet hair, or debris clogging the wheel. Clean thoroughly with a brush and vacuum.
• 4. Check wiring and connectors: Ensure the blower’s power connector is fully seated and wires are not burned or loose. Repair any damaged wiring.
• 5. Test the blower motor: Spin the blower wheel by hand; it should turn freely. If stiff or noisy, the motor bearings may be failing. A qualified person can test the motor with direct power. Replace the blower if it does not run properly.
• 6. Control board output: If the blower is good but not receiving power, the control board’s blower output or speed control may be faulty. This typically requires board replacement by a technician.
• 7. Restart and verify: After repairs, restore power and run the furnace. Confirm that the blower starts and Er11 does not reappear.