I suggest you get from Valencia by train to Barcelona, ​​to the Barcelona Sants train station, then by express train from the station to the airport (runs every half hour) and then by shuttle to Andorra- La Vella.

Train timetable can be viewed on the website www.renfe.es.

The timetable of the Barcelona-Andorra-La Vella shuttles on one of these sites: www.andorradirectbus.es, www.andorrabybus.com. Tickets are bought from drivers on site.