Electric Fan Thermostatic Switch - What temps?

[rob0r]

I noticed that my E34 rad has the provision for a thermostatic switch on the right hand side, what temperature ranges should I be aiming for? Also what is normal temperature that a normal thermostat opens at? Is there a known switch that everyone uses?

[lamby]

have you got air con?if not that switch is for the air con rad.

[rob0r]

The E30 doesn't have aircon, and neither did the donor E34 535i that the rad came from. You can see in the picture that the rad has a blanking bolt where a thermostat switch can bolt in, so I'm wondering what temp rating to get the switch at. I think I read someone used an 85-90 switch...

[gcs325i]

I think it'll depend on the temperature of the thermostat that you fit, we fitted a 80 degree stat and a 80/88 switch to run the twin speed fan.