Where is the radiator fan switch on a 97 Honda Prelude?

There is no switch. It comes on and turns off all by itself. A rad fan will not prevent your car from overheating anyways, it mearly fine tunes and regulates the temp. You have other issues. Change your thermostat, change your rad cap. Those are two of the simplest things. If that doesn't fix your problem then you have got bigger issues that will require a mechanics help.