Service and Test Whole-House Attic Fan

Turn the fan on and listen for grinding or squealing — these indicate dry bearings. Turn the power off at the breaker before any maintenance. Access the fan motor (usually in the attic). Apply 2–3 drops of non-detergent electric motor oil (SAE 20) to each oil port on the motor, if equipped — do not over-oil. Spin the fan blade by hand to check for wobble or drag. Clean the louver or shutter vents on the ceiling below with a vacuum and soft brush — clogged shutters significantly reduce airflow. Check the belt drive (if applicable) for cracks or wear. Test the thermostat setting: most whole-house fans should trigger below 80°F. Ensure the attic has adequate ventilation openings — a properly ventilated attic fan can reduce cooling costs by 10–15%.