I did mine a little differently.
I found out that the thermo switch was bad on my system so I just bypassed it by installing my own relay to make the connection when the compressor was on.
Since the thermo switch opens/closes the ground circuit on the fan, I cut it out of the system and used a relay to simulate what it does, based on status of the compressor.
Again this is for S13, not sure how it is on the S14 but for my A/C fan there are two plugs, both have 2 wires. One of the plugs is for the thermo switch, where if the circuit is completed, the fan kicks on. The fans by factory already have their own power and ground source if you had an A/C equipped car, so no need to create a new circuit.
That is what I did, and it works flawlessly for me so far.
PS, please excuse shitty drawing, I was terrible in art class.