I have used Family Tree DNA for my Carroll DNA testing.
Here is a blog that compares FTDNA and Ancestry:http://dna-explained.com/2012/08/14/y-dna-family-tree-dna-vs...
I personally believe that Family Tree DNA is far better than Ancestry DNA.
Take a look at the Carroll project at FTDNA, which is at:http://www.familytreedna.com/public/carroll
Then, try to find something like it at Ancestry.
Or, Google "Carroll DNA" and see what comes up.