This site has the pollen filter instructions (in case that is what you meant,
it is tricker then the air filter):

http://volvospeed.com/maintence.htm#Filters

For the air filter, just unsnap the metal tabs that surround the
airbox on the side. The coil lead wire also has to be pulled off of
a little plastic retainer. Then lift the top up and towards the engine
(it won't come all the way off, just swings up enough to slip in a
new filter). You don't have to remove any duct work.