Horn not working

Check the power to the horn first. Make sure there is power going to the horn. If not, then remove the horn button and make sure the connectors are intact and you have a good ground. Let me know

Also won't hurt to check for a horn relay

On a 93 Explorer, there are 2 options. Being a 93 Ford, it might be the same. There are no Guarantees.
If the truck has speed control, then there is a horn relay. It looks like it is under the dash near the steering column.
If it dosen't have speed control, it is only the switch in the steering column.
In my explorer book, it goes from fuse #8 to either the relay or switch, and then to the horns.
Try to run a jumper from the hot (+) terminal of the battery to the horn to make sure the horn actually works.

Just realized one more thing.
Check the fuse box under the hood. In my explorer, the power for the horn and several other devices routes first through the power distribution box under the hood.

The power distribution box I mentioned has both fuses and relays. Look in your owners manual.

Check fuse C (20 amp) in the engine compartment fuse box, located left side of engine compartment. If OK check horn relay, same location. If OK as well then horn switch on steering wheel is probably at fault.

DOES this truck have an air bag. If so DO NOT back prob any wires with power unless you disconnect it. If it does have an air bag it is possible you have a bad clock spring. Doese truck have cruse and all that at the steering wheel?

Does your cruse work? Have you tryed tapping on ht horn with a hammer while someone holds the horn button down. Sometimes a little jar will get them going again 8) NOS