or maybe the other way around, so, this just started happening tonight, (lucky me eh?) I start my car, turn on the compressors, then the compressors kick off and the horns start to go (HOOOOOOOOOOOONNNNNNK!) this is after the tank is full and the pressure switch kicks off. I am thinking that splicing into one of the wires that runs the small compressor and powers the relay for the K3’s might have been a bad Idea eh? I’m gonna re do the wiring and just run it straight back (Minus the new splice) and see what happens. This just started happening after I did that.
So where does the blown fuse come in? … after the horns blow?
Sounds like a short (i.e. compressor power wire shorting to ground via the horn relay).
alright, found the problem, The splice that I did on the compressor power wire was causing it to not be able to handle the amp draw for the compressor, so, I re did all the wiring, went out, tested it, FIXED!!! 
The horns honking must have been one hell of a power spike from when the fuse would pop and that spike just so happen to go to the solenoid, reason behind this, The compressors and horns are both grounded next to each other. That or maybe the horns were haunted by the souls of all the people I scared with the horns coming back to haunt me and the ritual to set their spirits free worked.
I’ll go with the “Haunted Souls” theory … but glad to see it’s fixed.
Somehow I knew you wouldn’t be out of action for long