Daikin furnace displays L3; unit may shut down during operation, sometimes after running for a short period.

Safety: Turn off power at the breaker and wait for all moving parts to stop before working inside the furnace.

Steps to check:

• Inspect blower compartment: Remove the blower access panel. Check the Daikin blower wheel for debris (insulation, plastic, wiring) that could jam or slow the wheel.
• Spin blower by hand: Gently rotate the blower wheel. It should spin freely without grinding or binding. If it is stiff or seized, the ECM blower motor bearings may be failing.
• Check motor wiring harness: Ensure the multi-pin harness from the ECM blower motor to the Daikin control board is fully seated and not damaged or burnt.
• Filter and duct restriction: A severely clogged filter or closed supply/return dampers can increase motor load. Replace the furnace filter and open registers.
• Reset power: Restore power and call for heat. If L3 reappears quickly, the motor or control board likely needs professional testing.

Overcurrent faults can quickly damage the ECM motor and control board. If the blower is not obviously obstructed, contact a technician to test motor amperage and replace the Daikin ECM blower motor or control board as needed.