I'm dealing with what I can only assume is an electrical demon. The car is mostly stock with the only exception being a "Code Alarm" aftermarket alarm that was installed by a Honda dealership in 2001. Car is a 1994 EX 4dr auto. My wife has owned the car since then (2001) and I've driven it as a daily driver for nearly 15 years now, the below issues are all new, starting in the last 6 months.

One issue is the wipers, they will run for about 5 minutes after you start the car, turning the wiper switch or misting the windshield doesn't so anything to stop them, but they do increase speed if you switch it to high, then turn off and function normally afterwards. Another issue is the horn buttons don't work immediately after starting the car, but after hitting the cruise control cancel button a few times, they start working again. Radio was having issues where sound only came from the left 2 speakers, then faintly (max volume you could barely hear it) from just the rear left, now the radio won't even turn on. Finally, my radiator fan will run even if the car isn't started, after engaging the key to On back to Off. But immediately after starting the car, the fans don't turn on unless the a/c button is engaged (in Texas that's pretty much year round, except for a few weeks in January) or the car has reached operating temperature (ie run for 15+ minutes).

Is there a single part that could be causing all these issues, like clock spring, ignition switch, or something else?

 

I suppose it's possible that something like the ICU is damaged, but they don't all sound connected. Possible a couple are connected. You can test this a bit by pulling the fuse(s) for the various items and see if some things start working normally. So, pull radio, wiper, and horn fuses to see if pulling one then affects the other. I can sorta see two connected, but I don't they all are

For the wiper, I would guess the relay is shorted/going bad/etc.
Located here:

The horn might be connected in some way to this short, but I don't think the radio is.

The radio I think is simply dying I don't think it's connected to anything else

The fans I also think might be a fan relay.

While it would be nice to have one item be the issue, at 26 years old they seem to be failing in "chunks" at this time. Although my car is not quite as old (1999), it had an air con dash failure, door lock failure, and several lightbulbs in dash and shifter light fail all within a few days/weeks of each other. Nothing connected them together, just being 20 years old they all happened to die.

Going back to the top, I would remove fuses first to see if anything changes (does horn fuse removal change wipers, for example).