Yes, AAS is a Scrabble word!

Letter values in Scrabble US: A 1, A 1, S 1.

Is it a valid word?

AAS is a valid word in the official Scrabble dictionary (US), the UK Scrabble Dictionary and Words with Friends (ENABLE).

an associate degree in applied science
a dry form of lava resembling clinkers
an international organization that provides a support group for persons trying to overcome alcoholism
an associate degree in arts

Also: associate in applied science, alcoholics anonymous, associate in arts.