Are child support payments that are direct deposited into an account exempt from a Garnishment?

Available exemptions for non-federal levies/garnishments are determined by state law. You should consult with your bank counsel on what exemptions are available in your state to insure you properly process a levy/garnishment.

What Ray said:

On the federal level

http://www.consumer.ftc.gov/articles/0114-garnishing-federal-benefits