How do I reduce noise from my HVAC system?

Tighten loose panels and screws on the furnace and air handler. Replace worn motor bearings or belts. Ensure ductwork is properly supported and not vibrating against joists or walls. Install vibration isolation pads under the outdoor condenser unit. Consider a variable-speed system that runs more quietly at lower speeds. Insulate ducts near the air handler to dampen sound. For persistent noise, have a professional inspect the system.