I Need Some Help With My Electric Fan

Fan has it's own controller then. I've seen that before, but can't think of the type of my head.
I also want to say it may be wired incorrectly. Is there a temp switch anywhere that you can see? Did rotating the knob adjust the temp the fan came on?

One red wire probably powers the fan motor. This is the wire that connects to the starter solenoid. You should have a fuse on this wire as well.

As for the other 3 wires, they are typical fan controller wires. Red would get power from a wire that is switched on with the ignition, black is ground, and green typically connects to the A/C clutch circuit as an alternate means of turning the fan on.

Now, I *think* swapping the black and green wire will get you what you need. The green wire can be taped up (or you can wire it to a manual override switch by installing a toggle and grounding the other end) and the black wire can be grounded. The red wire will get power when the car is on and you can use the knob to set the temp assuming there is a temp sensor wired directly into the controller and on the fan itself.

I'd trace out the red wire that goes into the firewall and see where it goes. if it just taps into the fusebox, the original owner must have tapped into a wire that sees constant power. I'd then disconnect that wire and tap into the low coolant sensor wire at the front drivers side of the car. This only sees power with the key on, so when you shut the power off, the fan turns off too.

That's my take based on the info you provided