The win gives the Bison (6-8, 3-0 Patriot League) three straight wins to open the conference portion of their schedule.
After Jesse Reed hit a jumper for American University to give the Eagles their first lead of the second half at 38-36, The Bison scored 13 in a row, capped by a Foulland jumper, to take a 49-38 advantage.
The Eagles never cut the lead below nine points the rest of the night. Hass and Brown combined for six straight at the line late to push the lead to 18.
Reed scored 13 for American University (2-12, 0-3). The Eagles have lost seven straight.