Furnace display shows E09, unit may shut down unexpectedly during operation, sometimes accompanied by a burning smell.

Safety first: Turn off power. Do not continue to run the furnace if you smell burning or suspect motor overheating.

• 1. Inspect blower compartment: Remove the blower access panel on the Thermia furnace. Check the blower wheel for dust buildup, foreign objects, or signs of rubbing against the housing.
• 2. Spin blower wheel by hand: It should rotate freely without grinding. If stiff or seized, the blower motor bearings may be failing and the motor should be replaced.
• 3. Check motor wiring and capacitor (PSC motors): Inspect wiring harnesses for heat damage. For PSC motors, test the run capacitor with a capacitance meter; replace if out of tolerance with a Thermia-specified capacitor.
• 4. Verify filter and duct restrictions: Ensure the air filter is clean and that return/supply ducts are not blocked. High static pressure can overload the motor.
• 5. ECM motor diagnostics (if equipped): Some Thermia furnaces use ECM blower motors with built-in diagnostics. Check for LED codes on the motor module and follow Thermia service literature.
• 6. If E09 persists: A new blower motor assembly matched to the Thermia furnace model may be required. This is typically a technician-level repair.