DIY aux fan wiring through radiator switch

[Garageaholic]

I was going to use the E30 aux fan directly to the battery through a toggle switch (using an in-line fuse)... But then i was thinking of.. instead of a toggle switch, why not use the temp switch on the radiator??

Does the temp switch on the radiator work like that? It's just a 2 prong switch.(for my e28 535i radiator M30 application). I guess when it gets hot enough, it makes the electrical connection, just like a regular toggle switch?

Would I be correct in assuming this?

[Garageaholic]

bUMPITY bUMP is it simply a regular "toggle" switch under a specified heat?

[arsevader]

I really am confused about what you are trying to do. The radiator temp switch already controls the AUX fan.

[Garageaholic]

I know, but since i'm doing the M30 conversion, there are 2 switches instead of 1 switch that the E30 wiring works off of... So in effect i'm kinda re-wiring it myself...

[nando]

there are two switches built into one, one for low-temp low speed operation, and one for higher temp high speed operation. the stock temp range is 90c-98c, but you can get an 80c-88c temp switch instead. if you replace it with a single temp switch the fan will only operate at one speed.

I'm going to the lower temp range switch, hopefully it will work out. I'd love to ditch the clutch fan, doesn't seem to do much anymore anyway.

[DanGillan]

i did it with my m50 swap. i used the radiator switch to activate my one speed electric fan when the switch comes on low temp. its wired to a relay to work even when the car is off (as long as the temp is still above the low temp switch) and I have it wired so the AC switch manually turns it on if the radiator switch doesnt for any reason. in short, yes you can use the radiator switch, it took me a while to think about and draw out my wiring diagram before i wired it up. take your time and figure it out

[Sean]

i did it with my m50 swap. i used the radiator switch to activate my one speed electric fan when the switch comes on low temp. its wired to a relay to work even when the car is off (as long as the temp is still above the low temp switch) and I have it wired so the AC switch manually turns it on if the radiator switch doesnt for any reason. in short, yes you can use the radiator switch, it took me a while to think about and draw out my wiring diagram before i wired it up. take your time and figure it out

Car to elaborate, Dan?

I was thinking of making my fan so it runs on two speeds - the slow at a certain temp, and than high at the higher temp. Then, if I wanted to, I could switch it on high in my car using the switch.

I'd basically need to wire something to use the rad-switch and get a relay for the switch in my car, right? You also wired yours so if the radiator temp was still reading above the certain temp, that the fan would continue to run?