My local Toyota Dealer wanted $250.00 to do this simple service. Since I had a hard time finding info about the Prius V Wagon I made this video. This video shows step by step how to access, remove, clean, and reassemble the Prius V and the cooling fan. Additionally I upgraded the fan by adding a filter to the fan and pre-filter to the duct. Hope this helps save you some time and money.
** UPDATE 4-4-2022** Pesaq in the comments said Toyota now has a filter for the duct that's underneath the passenger rear seat part number G92DH-47090.