The 3 wire fans are 2 speed fans....GC/F ECU(and everything else I`ve seen WRX/lib) has hi and lo speed fans....seems your fozzy doesn`t.

With-out looking at the various wiring diagrams .. I would think that you would need to connect the green and white wire from the loom to the active wire of you fozzy thermos so when the ECU wants to run either speed you fans will run/do something.

Alternatively using the WRX fans might be the best idear..if they fit.