Genaro:

It is all very well to say do not disable the front fan, but as far as I know mine has never turned on. I replaced it once because it was seized.

Now the second was also seized, I have disconnected one of the leads at the rad. The problem is that with out use they will bind up. They may bind up even with use. Not only that, the sensor is on the cool side of the rad. So it will be too late as they switch on 225 deg F. Think what the temperature must be on the hot entry if the other side is at 225. A better system would be to turn it on when AC is used and on sensing a lower temperature, say 200. Perhaps more use would keep them operational. I am planning to add electric fans on the puller side of the rad and disconnecting/removing the pusher fan entirely and removing the driven viscous fan altogether. There is a nice writeup on turbobricks mod section. Dave Barton did anice writeup as well.