Upvote:3
From American Airlines (click on 'Transportation Vouchers'):
Validity
Transportation vouchers will be valid for one year from the date of issue unless otherwise noted. Once expired they will not be honoured for reissue or exchange to a new voucher
so essentially, no, they're not valid. However if you phone or see them in person and get the right supportive customer service agent, you never know - they may be prepared to re-issue them.