I had a problem in the truck recently. The air conditioning went out. Right as the sultry steamy 90º Cincinnati summer started.
As I started looking into things, the lone (obvious) symptom was that the fuse had blown. The air conditioner would run if I replaced the fuse, but would go out quickly.
It didn't help when I let my XYL drive my truck one evening, and she didn't use the ham radio and had A/C the entire trip (roughly 20 miles). This was after I read something about a wire being stuck under the intake on a forum. However, it went out on me the next day.
So I took apart the truck. It didn't take long to realize that the intake was smashing the air conditioner compressor clutch wire (in the first pic - with the blue plug going to that thing with a belt on it). The second pic shows what that smashing really did - it wore the wire insulation down to the point where it could complete a circuit to ground via the air conditioning line (thus causing the fuse to blow).
So now the truck is fixed and I can operate! 73.