Problem With Horn

[rfresolo]

i have a 02 gmc savana van. about a month ago my horn just went off at 3:00 in the morning. i ran out and started pressing the horn to get it to stop and finally the fuse blew and it stopped. changed the fuse a day later and had no problems. 3 weeks later it does the same thing at the same time. now today i check the fuse block under the hood and the fuse was blown again. i changed it and i still have no horn. changed the horn relay and still have no horn. where do i do next. thanks

[MarkD]

Does the horn itself have an adjustment screw on it?