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Thread: Help! Wiring electric SPAL fan

  1. #1
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    Thumbs up Help! Wiring electric SPAL fan

    I am running a 55mm radiator, part 17112227281 (for S54 M-coupe).
    (This is a thicker direct drop-in. Still has plastic tanks, but was $250.00 new).
    I am keeping my stock temp. thermostat and radiator fan switch.

    I am removing my mechanical belt driven clutch fan.

    I am removing my aux. electric pusher fan.

    I am installing a SPAL VA18-AP13-59A (30100825) curved blade puller fan. This is rated at 2070 CFM at static pressure of 0.0” inches water gauge (at 0.1”sp as I estimate installed conditions it is 1950 CFM.) The current input is 17.6A at 0.1 sp.

    The physical install:
    I have not seen a picture of this installed. Does it just fit in the shroud? It looks like its own outer ring of the fan will act as a shroud and will not pull from the rest of the radiator outside of its 16” circle and would therefore make eliminating the shroud a good idea. Unfortunately the shroud holds the radiator overflow bottle in place. Do I keep the shroud? Do I cut away all but enough to support the bottle?

    The Electrical install:
    I want it to act as a two speed fan. I am not sure if I can get what I want with the Bosch 30A relay, just diodes, or how, but:

    I would like the fan to get less power and operate at a lower speed when just my A/C is turned on to assure air is running through my a/c condenser without wasting too much power.

    I would like the fan to operate at full speed when the fan switch on the radiator triggers it.

    I would like the fan to be at rest when neither condition is demanding it.

    This is understeer.com’s diagram:


    This retains the aux. fan. Every wiring diagram for this seems to leave in the aux. fan and runs the new puller fan at full speed when on.

    BIG NOTE! As I have spent far too much time reading countless threads about this and have read everyone’s reasons for leaving the fans alone, let me say I am asking two questions and am not interested in a debate over why someone would or would not do this.

    1. Leave or modify the shroud?
    2. Can I wire it as a 2 speed? How?

  2. #2
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    Just dropping in to check out yet another cooling-issue related thread (funny how the cold weather makes them start coming up.)

    FYI, I looked up the aux fan and it's $600 bucks from bmw.. a little over half that from the mail order places.. still, that's an expensive fan do drop out! If it offers no parasitic loss why not leave it in for better AC in the summer?
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  3. #3
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    I'm removing it because it blocks airflow and increases static pressure on the puller fan if it is sitting in front while off. If both fans are on, there is a huge electrical draw. One fan's airflow is going to overpower the other with just the radiator sandwiched between and that is just a stupid setup. The aux. fan does not have a sealed bearing and is not too wonderful quality of a fan.

    I like the idea of redundancy, but keeping it messes up the function of the puller fan.

    I know someone is bound to mention changing to a setup with two smaller puller fans. This setup ignores and/or blocks off the majority of the larger radiator and cools less than one 16". (Actually cooling the coolant in the radiator, not just adding CFM. Two smaller fans do not equal one larger in surface area).

    If there is an excellent quality yet reasonably priced 2-speed 16" fan out there that solves this, let me know- I have not bought the SPAL yet.

    I'm really hoping someone has the answer to this without spending lots of time questioning the setup. Nither stock fan is staying. Nothing will change my mind on this.

  4. #4
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    here is the pics I have seen on the subject (it isn't my car):


    maybe though you could just modify it?
    double check with bimmer95 maybe but I thought if you just spliced the thick and thin (hi and low) wires together, you make it two speed. the difference in the speeds is determined by the thinkness of the wires, so it should work correctly.
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  5. #5
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    Mech:
    Too bad neither picture is showing how the overflow bottle is being held in place. It sits a lot more centered than keeping the shroud would. I think keeping the shroud would have it sticking above the top of the radiator, which would never work.

    Elec:
    I don't know the internals of the relay. My understanding (I may be wrong)

    The fan is getting it's current directly from the 12V wire with 30A fuse going to the #30 on the relay, and it operates at full power any time it is on.

    The high temp and low temp (thicker or thinner?) wire are just acting as a switch and not supplying the current.

  6. #6
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    Ok I understand your point, but the AC condensor is offset from the main radiator, and there is a gap between them (which is why BMW put the second aux fan in front of the AC condensor, so airflow would be directed right at the condensor.)
    There is absolutely no way that a spal fan at half speed is going to pull air through the condensor, air takes the path of least resistance and the majority of the air will go through the radiator (top half) instead of the lower half that the condensor sits in front of. Even if it goes through the lower half of the radiator, air will get sucked in between the gaps of the radiator and condensor.

    One option would be to leave the aux fan AS IS except cutting the coolant switch wires, the fan should still turn on when the AC is turned on, yet won't block anything when the AC is off (the fan will just windmill at highway speeds.) When the coolant temp switch turns on, the SPAL fan will turn on. You're getting a little closer to your needs. Why is the extra air flow required in the first place? If the car isn't overheating.... you seem to be making things more complicated.
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  7. #7
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    The ultimate goal is preparing and bulletproofing the cooling system so it can remain when I drop an LS1 in instead of the M50, but that is a major tangent. I do not know which A/C condenser I will use with the new engine yet.

    You may be right about the offset location and gap between the condenser and the radiator. The lower speed for A/C does not need to be half, but needs to be sufficient to keep the air flowing through the condenser. I may need to see if I can move the condenser to in front of the center of the radiator. I really do want that Aux. fan out of there.

    Cold weather? I live in Arizona!
    Last edited by DaveAZ; 01-29-2005 at 09:24 PM.

  8. #8
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    Quote Originally Posted by DaveAZ
    Mech:
    Too bad neither picture is showing how the overflow bottle is being held in place. It sits a lot more centered than keeping the shroud would. I think keeping the shroud would have it sticking above the top of the radiator, which would never work.

    Elec:
    I don't know the internals of the relay. My understanding (I may be wrong)

    The fan is getting it's current directly from the 12V wire with 30A fuse going to the #30 on the relay, and it operates at full power any time it is on.

    The high temp and low temp (thicker or thinner?) wire are just acting as a switch and not supplying the current.
    yeah, I wish it would show how they attech the overflow bottle.

    there are some good threads on the topic buried deep if you do some searches for aftermarket electric fan, etc.
    Hold on let me get my laptop and read this on the toilet.
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  9. #9
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    Quote Originally Posted by DaveAZ
    The ultimate goal is preparing and bulletproofing the cooling system so it can remain when I drop an LS1 in instead of the M50
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  10. #10
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    I can't even tell you how may threads I read on this, and any with pics suffer from the big red "X".

    Electrically everyone is keeping the aux. fan.

    As I said, the engine swap is a huge tangent.

  11. #11
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    yeah time seems to break all hyperlinks....

    if you are removing the aux fan, why don't you just wire the new fan up to the stock aux fan wires? then you don't even have to use bimm95's diagram.
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  12. #12
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    one more thing: how many wires is the new fan you got?
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  13. #13
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    The SPAL fan has just the two wires as shown in understeer's diagram.
    I have not bought it yet- I am waiting to solve this issue first in case I end up switching to a different fan. The SPAL seems to be the best quality out there and is affordable. If it had three wires and I could control the current to each it would be ideal. I'm sure there is a solution to this. I am not electrical.
    I'm going to bounce this off an electrical designer and see if there is an easy solution that I do not know.

    This fan is the one almost everyone is using for this, aside from their slimline model that I do not need because I have no space problems that FI (forced induction) people do.

  14. #14
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    To add to the Understeer wiring diagram and supply some more information:

    The existing to be removed aux. electric pusher fan has three wires: black/blue stripe, blue and green. (At the point of the shroud-I did not check what reaches the fan motor.)

    The fan switch on radiator has three wires: black/blue stripe, blue, and brown. (Mine is a late 1992, perhaps the colors change on later models)
    Last edited by DaveAZ; 01-29-2005 at 09:46 PM.

  15. #15
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    One more thing I thought of, people are using the lower flowing fans because technically speaking they don't need a fan at all, it's just to prevent too much heat soak and temp build up when sitting still on STOCK cars using the fan delete.
    If you've got an engine like the LS1 in there, you might want to think about the new SPAL extreme fan, which flows 3000 CFM! It's 16.3, and costs $230, but I think it's probably worth it for this situation. Hell it probably makes your car faster below 30mph
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  16. #16
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    i found this thread that seems to be a good one:

    http://forums.bimmerforums.com/forum...t=electric+fan
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  17. #17
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    Thanks, I saw that thread. It doesn't help. Bimmer95 is Understeer.com (see my original post for what he was describing) It does seem to rule out diodes.

    The Engine Tangent:
    The LS1 stock actually has a smaller radiator than an M3. The only running example of the LS1/E36 combination in the USA that I know of has a 16" pusher off the radiator swich and some pullers set to a lower temp that never came on. He has no A/C, so the condenser and low speed were a non-issue. He is using the stock M3 radiator which is smaller than mine as well.

    Pullers are better than pushers, and I should have the room, unless the intake ducting gets too big. Perhaps switching this idea to a pusher fan will kill the condenser bird. I still have the wiring question.

    A link to his cooling notes:
    http://nash8503.com/Cooling_System.html
    Last edited by DaveAZ; 01-29-2005 at 11:42 PM.

  18. #18
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    If you're straight up replacing the stock aux fan with a Spal unit, the most you'd have to buy would be a resistor, no relays necessary. Think about it.
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  19. #19
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    where can u find that bosch 30a relay shown in diagram above....under microfilter, behind glove box (and if so where)?

  20. #20
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    you have to buy one and wire it up. its not hard at all.

    i dont see the reason for a relay. i just wired mine up to a switched ign source. (the windshield washer pump)
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  21. #21
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    well the problem is someone put a aftermarket aux fan in and jerry rigged the wiring. when i went to replace it with the new oem aux fan i connected it up and the fan turned on when the car wasnt even on. i unplugged and noticed a 30a relay with a wire from the compressor 12v and pos and neg from fan i believe. I wanted to know where that relay is suppose to go so i can wire properly therefore turning the fan off when the car is off.

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