The screen de-mist ducts and the face level ducts are all attached to the dashboard. The heater box and the floor ducting is attached to the car. There is a join between the two that comes apart when the dash is removed. The only way to get to the ducts is to remove the dash - it is designed to come out for repairs and maintenance so quite straightforward. It took me about two hours to remove mine. Three hours to put back in
