Strange noises from your furnace can indicate various issues. Rattling may suggest loose components while banging or popping noises could signal dirty burners or ductwork expansion. Screeching or squealing sounds may result from a worn-out belt or motor bearings. Whistling noises may indicate airflow restrictions. Ignoring these sounds can lead to further damage or breakdowns. Contacting an HVAC technician for inspection and repairs ensures the safe and efficient operation of your furnace, resolving any underlying issues causing the noises.