I know Clinton won 2-5A in 1997, and they won 4AAA a couple of years ago...That's just if we're talking about since AC has been good. They also won their region/district in 1992, and I think maybe once or twice in the 80s, but I'm not really sure. Before that, I honestly have no idea.
Up until 1999, the series between AC and Clinton was tied at 7-7. Both teams had a couple of three-game streaks, but since then it has swung heavily in AC's favor.
I think AC would've had a district championship in 1997 in 3-4A, but they had to forfeit something like 5 games because they played an ineligible player. Their record was changed from something like 6-1 at one point to 1-6 or something like that. Really, the penalty was probably harsher than necessary. However, I don't know that they've won their region or district since then, and I doubt they ever did before that. I could be wrong though. They certainly have been pretty strong, but they've always been in districts with very tough competition.