Wiring aftermarket aux fan

[Tylerse30]

First post, just transferred from bimmer forums,
Ok so removed my stock fan because it was ruined in an accident, bought an auxiliary fan from advanced auto, has a blue wire and a black wire, I want to wire the fan to a switch, I have a switch in my center console, 2 prong toggle, even a diagram drawn on paint would help me, I need to know where to hook up the wires and fuse, to assentially turn the car on, and have the aux fan on, and through the toggle switch I can turn the fan off if I need too. Where do I go from here?

[jlevie]

If you simply want to operate the fan with the switch, pick up power from where the main battery cable connects at the power point in the engine bay. Run that through a fuse, to the switch, and then to the fan, and ground the other side of the fan. Use at least 12ga wire and a 30a fuse.

[Tylerse30]

Awesome, yea I thought about that, it comes in around the passenger side of the bay right? I have wiring from the fan through the throttle cable grommet, into a fuse, into the switch, but your saying connect it to the battery, then the fuse, then the switch? And the wiring coming from the fan is like a 16 gauge, little smaller than a 12

[Gregs///M]

This is the way I would do it on my car. Using a relay located in the engine bay. This will avoid high current wires running into the cabin. You can use low current, thinner wires to run to the switch.

[jlevie]

You want the fuse as close as possible to where power is supplied.

While this is a simple way to wire up the fan it has the disadvantage of the fan operating any time the switch is on, regardless of whether the engine is running, and the disadvantage of the fan not coming on automatically when needed.

The better way to install an electric fan is to add a thermo switch that trips at 82-83C to the radiator and use that to control a relay whose coil power is from a Hot in Start and Run circuit. You can put a switch in as a manual override for the thermo switch.

If the fan has 16ga wires, I suspect it isn't going to move enough air to substitute for the engine driven fan. A 2000cfm electric fan is roughly comparable to the engine fan at idle. A fan like that will draw more current than a 16ga wire can handle.

A few words of caution. Don't mount the fan with anything that passes through the radiator. Doing so can result in the fan mount wearing a hole in a fin tube in the radiator.

[Nick_08]

http://www.summitracing.com/parts/PRF-30101/

Specifically for use with I/O switches.

http://www.e30tech.com/forum/showthread.php?t=105294

This is how to wire up your electric fan to automatically turn on using the stock temp switch.

[Tylerse30]

Thank your for all the info guys!!!