My air duct is brand new. Should I clean it?
All new air conditioning and ventilation systems for human occupancy are expected to be handed over according to the standard EN 12599 – see section “Is there anything important new in the area of air conditioning and ventilation systems?”. In this case you have received from your supplier documents related to your air conditioning and ventilation systems like inspection plan, cleaning plan, etc. And according to EN 15780 each new duct has to satisfy cleanliness level according to its cleanliness quality class when it is handed over.
For other countries please check your local standards and legislation.