It's under glove box. Doesn't look too difficult. Section 23 of that manual you downloaded.

good luck

 

(shoulda read this first before responding to his private message...) See, I told you someone who has actually owned one will probably chime in. Here's my response just for giggles.

I've never owned a '94 so I'm probably not the best source. Please post this so you'll get someone who has actually done that job. And others can benefit too.

The "fan timer module" is buried somewhere under the glovebox. Try searching for that particular text. Aside from dismantling the glovebox lid, etc, I think it's otherwise plug-&-play.

That module is responsible for the logic between the 2 fan-switches & the operation of the fans. Seems logical that a messed-up timer module would be the motivation for hard-wiring the fan with a manual switch.

However, under the circumstances, I'd also suspect problems with the wiring harness. So your testing should include whether any of the wiring has shorted to ground. I've heard that certain years the wiring is particularly tasty to rodents. I don't know if the timer module is very spendy, but you might want to rule out wiring before buying one.