Horn & Wiper Fluid

A few weeks ago. My cars blower wouldnt work. Then while driving down the road the horn and wiper fluid would spray and beep in unison in and erratic way. Then today while replacing the rear brakes the same thing. The horn was blowing and the sprayers were squirting fluid at the same time and again in a erratic way. It stopped when I smack my hand on the fuse box under the hood which was already open. The doors locked and the car wasnt running and the keys were in my pocket. We had it at the garage in between these too incidents and they couldnt determine the problem?