In 1975, at 17 years of age, while representing Pine Crest High School at an Amateur Athletic Union swimming meet, Coan broke Jim Montgomery's 12-day-old 100 metre freestyle world record.

[1] Later that year, under the coaching of Jack Nelson, Coan won three gold medals at the 1975 FINA World Championships in Cali, Colombia.

[2] He continued his winning run at the 1975 United States National Swimming Championships, where he won a gold medal in the 100 yards freestyle event.

Coan did not participate in the 1980 Summer Olympics due to the boycott by United States to protest the Soviet invasion of Afghanistan.

[3] Current athlete nephews of Andy are Matthew and Kyle Coan, both raised in Fort Lauderdale and coached by Jack Nelson while combining for 8 state championships while attending the Saint Thomas Aquinas High School.