Do you need to replace ductwork when replacing AC?

You do not automatically need to replace your entire home's ductwork every single time you install a brand-new air conditioning system, provided your existing ducts are clean, structurally sound, well-insulated, and properly sized for the airflow capacity of the new equipment. However, if your current duct network is severely undersized, heavily damaged, leaking excessively, or contaminated with mold and rodent waste, keeping it can choke your new high-efficiency AC, reducing its performance and lifespan. During a system upgrade, a qualified HVAC technician should perform a Manual D calculation and inspect your ducts to determine if repairs or partial replacements are necessary. You can verify the health of your system when professional airflow testing confirms that your existing ductwork matches the static pressure requirements of your new air conditioner.