A furnace burning smell can come from five common sources: dust burning off after summer, factory coatings on a brand-new furnace, an overheating electrical part such as the blower motor or capacitor, a worn blower belt on older furnaces, or a clogged filter that restricts airflow. Each one has a different fix, and only some are safe to wait out. This homeowner-friendly guide from Calgary's Purcell Heating & Air explains every cause in plain language and tells you exactly when a technician needs to take a look.