Author Topic: wiring an electric fan (Read 6136 times)

johnwoo · « **on:** November 27, 2011, 09:41:37 PM »

hey guys want to see if anyone has a diy with diagrams and pics on how to wire an electric fan to a toggle switch. i know i can use the aux fan circuit but i would like to keep that there and have a backup puller behind the radiator since i deleted my clutch fan for the hot southwest summers.

i searched but couldn't find a diy for it. my main questions are im thinking i need to run a relay and a power source for the fan. any suggestions on where to get the power from and how to wire it up. thanks for all the help. looking at a 16" spal puller behind the radiator. thanks

vpilarry · « **Reply #1 on:** November 30, 2011, 09:48:24 AM »

Here's what I did: The late E36's and Z3's with the M44 had an electric puller fan with a shroud that fits our radiator/shroud attachment points (same radiator IIRC). Remove the front aux fan (its not going to be needed anymore and is not large enough to be your primary engine cooler), install the M44 electric fan (behind the radiator, of course), install the 80�/88� degree fan switch (from the early E36 M42) in the radiator, wire the new fan into your existing aux fan wiring harness (you will have to add some wiring as the new fan harness is not long enough). Now the new electric fan will come on when the engine heats up and when you turn on the AC like the aux fan did.

DesktopDave · « **Reply #2 on:** November 30, 2011, 11:09:17 AM »

+1 on that...the OEM BMW parts are the best.

There's a million ways to skin this cat, but I'd do something like this:
Any aftermarket fan should have a standard 4-pin relay and fuse. I'd mount that to the car up front, maybe near the AFM. I'd strongly suggest disconnecting the battery until all wiring is completed. I'd tap into switched power under the dash to the toggle switch, maybe off the stereo harness. Then I'd run the other toggle switch terminal wire through the firewall plug to relay terminal #85. Next, wire relay terminal #30 with an inline fuse right off the power block on the passenger side firewall. Then, run the fan power off relay terminal #87. Finally, wire both relay terminal #86 and the fan ground to the front grounding post (driver's side inner fender).

johnwoo · « **Reply #3 on:** November 30, 2011, 10:14:11 PM »

Quote from: DesktopDave;108501

+1 on that...the OEM BMW parts are the best.

There's a million ways to skin this cat, but I'd do something like this:
Any aftermarket fan should have a standard 4-pin relay and fuse. I'd mount that to the car up front, maybe near the AFM. I'd strongly suggest disconnecting the battery until all wiring is completed. I'd tap into switched power under the dash to the toggle switch, maybe off the stereo harness. Then I'd run the other toggle switch terminal wire through the firewall plug to relay terminal #85. Next, wire relay terminal #30 with an inline fuse right off the power block on the passenger side firewall. Then, run the fan power off relay terminal #87. Finally, wire both relay terminal #86 and the fan ground to the front grounding post (driver's side inner fender).

thanks for your help and tip. do you have pics. i don't really have any clue as to where these wirings are.