How eliminate Bad odor coming from vents?

To eliminate bad odors coming from vents, start by replacing or cleaning the air filters, as dirty filters can trap odors. Next, inspect and clean the ductwork to remove any dust, mold, or debris that may be causing the smell. Additionally, check for any moisture issues or leaks, as stagnant water can contribute to unpleasant odors. Finally, consider using air fresheners or odor-neutralizing sprays designed for HVAC systems to help mask or eliminate any remaining smells.