Announcement

Collapse
No announcement yet.

How to: Stand Alone Electric fan wiring

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

    How to: Stand Alone Electric fan wiring

    **Please see the 2nd post of this thread- I had to change my wiring setup due to the fact that once the engine is cut, coolant flow is stopped and with constant power to the switch- the coolant temp won't decrease for at least 5 minutes- which is just too long**

    Chiming in here with my modified electric fan setup. I've used the thread below for wiring up my electric fan using the Aux fan wiring.



    Short story: I followed that on how hook directly to the Aux fan wiring with a 80C switch. Easy to do, simple and not a lot of electrical cabling. I was running a SPAL 16'' Puller as my primary cooling fan for a few months.

    This worked like a charm- except under the ONE scenario: If the temp switch kicks on the fan at 80C and starts cooling, and I was ready to park or turn off the car and the fan was still on- the fan would obviously lose power. IF I had to turn the car back on for whatever reason (maybe to move the car after you parked it) and the temp was still over 80C- the startup of the ignition I would blow the stock 30A aux fan fuse every time. I found out that this can happen when switching from the +12v of the battery (ignition ON but engine OFF) to the new +14.3v you get from turning over the engine and obtaining the power bump from running from the Alternator. By the way- I never blew the in-line fuse I added from the +12v of the fan- only the 30A fuse in the fusebox.

    Also- which is a great point on why I modified it- was that say you are getting ready to pull into your destination, you might be idling a bit to find parking etc etc and the car gets up to 80C. The fan kicks on and might still be running when you turn the car off. Which is fine. But if you need to turn the car back on again, the thermo switch on the thermostat- which goes to the DME- will tell the DME that the engine coolant is too hot and don't supply fuel. So you get this hesitation when trying to start up. I can't get a definite temperature of what the thermostat DME switch reads that tells the engine that it is too hot. I only found out what resistance it reads at certain temps. If you know- I would really be interested what this threshold is.

    Anyway- my plan was to remove the fan from the Aux wiring fuses/relay and run power directly to a new relay that has constant +12v w/o the ignition on. First tried to wire up a new relay and fuse to the stock fusebox. Wasted my time since I couldn't find the correct female blade inserts for the fusebox. Decided to do a completely standalone setup.

    Here is what I used and how I wired it in:
    Hella 30A Relay and weather proof wiring harness $15
    - Relays are pretty much all the same from what I found. Went with this one since I decided on mounting it stand-alone from everything else and tried to make the install clean. Sure you can use a standard Autozone 30A relay, but finding the wiring harnesses are hard to find locally and at the end it will probably be a pretty messy wiring job. Installed mine on the side of the fuel pump relay cover.


    30A In-Line fuse holders $4/each
    - Used this instead of using the Accessory fuse holder (some have used this stock fuse holder for other things) Put one from the +12v Constant coming out of this stock fuse holder to terminal 30 on the relay. Used the other one for the +12v for the fan.

    Here is my drawing and relay layout.





    Relay Wiring
    Terminal 30: +12v (12GA wire) constant from stock accessory fusebox (with In-line 30A fuse) Updated- switched this lead from the constant 12v+ to the Constant OFF/Ignition ON 12v+ accessory lead
    Terminal 85: Ground (12GA wire)
    Terminal 86: Trigger switch (14/16GA wire) I'm using my 80C thermo switch with a manual override switch that I used a extra fog light switch and mounted it next to the defrost/hazards (to turn on the fan under 80C if needed) You need to tap into a 7.5 fuse that has constant +12v so fuses 21, 22 and 23 are always on. I tapped fuse 21 (not 10 as pictured) since it is used for other switches on the car. Run a wire from here, to the thermo switch. Then a second wire back to terminal 86. Updated- switched this to the another Ignition ON 7.5 fuse (Used #19 Mirror Control)
    Terminal 87: Fan +12v (12GA wire) used an in-line fuse here to protect the fan. Mounted it near the fusebox for easy access.
    Terminal 87A: NOT USED (unless you need power to something that is ALWAYS on and OFF when the fan is ON)

    Notes:
    Make sure you invest in good butt connectors, crimp (or solder if you prefer) and electrical wrap. I hate glossy electrical tape, so I purchased some premium wire wrap.

    Thats about it! It's not the most complex job, but it gets it done and doesn't rely on anything stock. Hopefully this will help out people who might see the same issues. There are a few threads around that I've read about their fans blowing fuses left and right. This should be the solution. Good luck!!
    Last edited by Klug; 06-15-2015, 08:12 AM.
    555Garage - Kingston, PA

    '13 BMW e70 X5 35d
    '95 BMW e34 525i
    '92 BMW e30 325i S52 Vert (Quade the Vert)
    '92 Range Rover Classic
    '90 Range Rover Classic
    '89 BMW e30 325i Coupe (The DIRTY30)
    '81 VW MK1 Rabbit Caddy Diesel
    '76 Honda CB550K Cafe/Brat
    '67 Pontiac LeMans
    '24 Model T Depot Hack
    ....And a bunch of Motobecane, Puch, Garelli, Batavus and Honda 49cc-78cc Mopeds...


    #2
    Well my wiring was all correct- however my design was a little skewed :(

    If the temp in the radiator is 80C and the fan is on while turning off the engine- the fan will stay on and not shut off (for at least 5 minutes which is too long). This is because once the engine cuts power, the water pump which creates the flow of coolant- stops. So the coolant that was 80C is not moving around, so the temp switch stays on unless I turn the car back on and the cooler coolant starts flowing again over the switch.

    I ended up switching a few things and have updated them above. Needed to switch the lead accessory wire from the Constant to Ignition ON 12v+. Then the switch power I tapped into fuse #19-Mirror control. Just those two changes- took me all of 5 minutes. At least the fan is independent from the stock wiring so I shouldn't blow any fuses anytime soon, a much better design than using the stock aux fan relays.
    Last edited by Klug; 06-15-2015, 08:06 AM.
    555Garage - Kingston, PA

    '13 BMW e70 X5 35d
    '95 BMW e34 525i
    '92 BMW e30 325i S52 Vert (Quade the Vert)
    '92 Range Rover Classic
    '90 Range Rover Classic
    '89 BMW e30 325i Coupe (The DIRTY30)
    '81 VW MK1 Rabbit Caddy Diesel
    '76 Honda CB550K Cafe/Brat
    '67 Pontiac LeMans
    '24 Model T Depot Hack
    ....And a bunch of Motobecane, Puch, Garelli, Batavus and Honda 49cc-78cc Mopeds...

    Comment


      #3
      Hey thanks former self for making this thread- needed to figure this out for the other e30 I just got!
      555Garage - Kingston, PA

      '13 BMW e70 X5 35d
      '95 BMW e34 525i
      '92 BMW e30 325i S52 Vert (Quade the Vert)
      '92 Range Rover Classic
      '90 Range Rover Classic
      '89 BMW e30 325i Coupe (The DIRTY30)
      '81 VW MK1 Rabbit Caddy Diesel
      '76 Honda CB550K Cafe/Brat
      '67 Pontiac LeMans
      '24 Model T Depot Hack
      ....And a bunch of Motobecane, Puch, Garelli, Batavus and Honda 49cc-78cc Mopeds...

      Comment


        #4
        Originally posted by Klug View Post
        Hey thanks former self for making this thread- needed to figure this out for the other e30 I just got!
        Lol
        RHD OBD2 M50b25 turbo build thread:
        http://www.r3vlimited.com/board/showthread.php?t=384800

        Comment


          #5
          I used this write up to install a Spal 16 inch Puller fan in my e30 vert. One thing to note. The wiring harness has little numbers on each of the wires that come off of the relay holding clip. I assumed that those numbers on the wires corresponded to the terminal numbers on the relay itself. As the relay has markings on it like this 86 -1 , 85-2 and so forth. So I connected all of the wires up based on those associations. That was incorrect and the fan did not work as intended the first go around. Once I discovered that the wires that were labeled with the numbers did not match up with the actual terminals and wired it properly everything works as expected. Its nice that you have already experimented with constant power versus ignition switched power and listed the reason not to go with ignition switched power. Thanks for the write up!

          Comment

          Working...
          X