[BoxsterSteve]

Don't know how much this helps... it's a copy and paste from Rennlist a few years ago.


Radiator Fans

The mod consists of installing a switch that will allow you to turn on the high speed radiator fans at any time, while maintaining the automatic operation of the fans. The same thing can be done for the engine compartment fan.

Connect a wire to the ground of the 2 high speed fan relays located on the relay carrier located in the driver’s side foot well. The relays are #20 and #22. Feed this wire to where your switch will be located. Connect the wire to one side of the switch. Connect another wire from the other contact on the switch and then connect the other end of this wire to a chassis ground point.

With key on, this switch will now immediately turn on both radiator fans providing maximum cooling. When you turn the key off, the fans will continue to run for about 5 seconds until the relay shuts down. Your fan operation remains normal when the switch is off.

If you are adventurous, you can automate the operation of this switches so it will switch off at a specific speed, or operate when vacuum is present only, etc.

You can choose any style switch you want and even use Porsche switches. I simply used a toggle switch that I installed in the batwing.