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E39 Aux Fan Upgrade How To

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Big Bronze Rim

E39 Aux Fan Upgrade How To

Post by Big Bronze Rim » Tue Sep 01, 2009 2:24 pm

E39 Auxiliary/Condenser Fan Upgrade How To

By Bradley Denton

Purpose:
To improve cooling and air conditioner performance by upgrading the 20 year old electric auxiliary fan.
Image

The Fan:
The E39 5 Series has an excellent auxiliary cooling fan installed from the factory. For those that have hear it running on high speed, they will tell you it sounds like it means business. While I have no definitive CFM rating for the fan, I am willing to bet that it out performs most, if not all aftermarket fans on the market. It has a side benefit of coming installed in a very nice shroud with louvers to reduce drag at freeway speeds and improve flow through the fan at low speeds. The fan is roughly 16" in diameter and has curved blades. I am using an OE replacement fan made by DEPO parts for a 99-03 e39.
Image

The Install:

Since I am using a modern parallel flow condenser the install will be slight bit different than if the original condenser was installed. The fan in the e39 is on a 50A circuit which means that the stock wiring for the e28 aux fan will be insufficient as it is on a 25A circuit. New wiring will be required. I wanted to be able to have the fan run on a high and low speed so I planned to use the resistor set that came with the electric fan.
I should note here that I made a bit of a mistake as I learned after sourcing the fan that these model years use a PWM (pulse width modulated) fan control instead of resistors to control fan speed. Only the 97 and early 98 models have the fan with a three speed resistor pack. I removed the PWM controller and installed the factory resistor pack from my old stock fan. I have plans to build a PWM controller for the e39 fan so stay tuned for this upgrade ( I am a strange mechanical engineer and enjoy electronics projects). This configuration will require two relays. Using the original low and high speed fan relays, I wired them to act as the control circuit for a new pair of 50A relays mounted on the core support. Using a run of 2 pair shielded wire, I wired them up. The wiring I used can be seen below.

Image
Wiring schematic (yes, I know, I am type-A and used the original ETM schematic and modified it). There is some optional wiring and it is noted in the drawing.

Image
Resistor Pack Mounted
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Two Pair wire for control circuit. You can connect the two ground wires together as shown.
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Relay control wires spliced into original fan wiring. Since it is only controlling a relay, the wires do not need to be a large gauge.
Image
Relays and wires mounted and ready to rock.

Since I have an intercooler mounted on my car I had to remove the lower shroud to get it to clear. This would not be necessary w/o the intercooler. Here are some shots of the mounted fan.
Image
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Performance and Conclusion:

The fan on low speed seems to move as much air as the old fan did on high speed. Since I want a little bit more performance on the low speed setting I am planning on sourcing a 0.2 ohm resistor from an early e39 to replace the e28's 0.6 ohm unit. On high speed this fan just plain rocks. It moves an amazing amount of air. With the engine off it has enough guts to spin the stock clutch fan with a healthy fan clutch. That's what I'm talking about. It is a bit loud in front of the car, but it is almost not noticeable from inside the car with the windows down (who wants to do that though when you are rocking the AC in 104? heat). All in all I am very pleased with the fan upgrade. It looks exceptionally stock (too bad it's covered by the cowl cover) and performs as I had hoped it would. The only thing I would do differently would be to have purchased an earlier model fan so it had the resistor pack. Now that I have this one though I will be implementing my PWM controller. When (if) I get around to it, I will update this thread. Hope you guys enjoy and give you an option when replacing your aux fan.

mistryman

Post by mistryman » Wed Sep 02, 2009 12:08 pm

Nice work.

douginky

Post by douginky » Wed Sep 02, 2009 1:05 pm

That's great news and info. I'd thought but not tried the same thing. My E39 sounds like it would suck my dog into it. I'll bet it kicks a$$
Thanks !!!!

horsetan

Post by horsetan » Wed Sep 02, 2009 2:48 pm

Ingenious upgrade. 8)

Wonder if this would fit into the restricted space of an E24, as opposed to an E28?

The Sixer Kid

Post by The Sixer Kid » Wed Sep 02, 2009 4:22 pm

horsetan wrote:Ingenious upgrade. 8)

Wonder if this would fit into the restricted space of an E24, as opposed to an E28?
If anything, I think the e24 has more room.


As usual Brad, very nice write up.

horsetan

Post by horsetan » Wed Sep 02, 2009 9:02 pm

That fan will have to go on my "swipe one if ye get the chance" list

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sskang
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Post by sskang » Fri Sep 04, 2009 6:32 am

Excellent project execution!

For someone living in a similar climatic condition in the summer, it seems like a fabulous upgrade!
sskang
1987 M6 Alpinweiss
Tokyo, Japan

"Aller guten Dinge sind Sechs"

horsetan

Post by horsetan » Mon Sep 21, 2009 9:00 pm

Could we have permission to also post this article in the UK 5-Series Forum (E28 section)? :idea:

jacko
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Post by jacko » Thu Jul 30, 2015 4:37 pm

I'd be curious to hear from anyone who has done this mod on an e24.

Also, how reliable have these Chinese aftermarket fans been?
Jack
Arlington, Texas. USA

1989 635csi
Automatic

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sansouci
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Post by sansouci » Thu Jul 30, 2015 8:47 pm

Do you have a P/N and supplier on that fan?
Sansouci
84 E24 633Csi Auto, Bronzit/PearlBeige 6997510
93 E32 740il M60 Auto, Alpenweis/Ultramarine
60 535i M30 5-speed Green/Beige (crushed)
71 240Z 4-speed White/Blue (rusty & sold)
65 396 Chevelle 4-speed, Marina Blue/Black (stolen)

jacko
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Post by jacko » Thu Jul 30, 2015 9:37 pm

64548380780

A couple different suppliers. All look identical. All over ebay and the usual suppliers.

Look at bmwbuddy
Jack
Arlington, Texas. USA

1989 635csi
Automatic

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sansouci
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Post by sansouci » Fri Jul 31, 2015 1:58 pm

Interesting how this seller described it as a Behr/Hella product. Guess they all buy from the same Chinese factory.



http://www.ebay.com/itm/Behr-Hella-Auxi ... 49&vxp=mtr

Here's a Siemens/VDO labeled product
http://www.ebay.com/itm/1997-1998-BMW-5 ... 65&vxp=mtr
Sansouci
84 E24 633Csi Auto, Bronzit/PearlBeige 6997510
93 E32 740il M60 Auto, Alpenweis/Ultramarine
60 535i M30 5-speed Green/Beige (crushed)
71 240Z 4-speed White/Blue (rusty & sold)
65 396 Chevelle 4-speed, Marina Blue/Black (stolen)

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Finally6
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Post by Finally6 » Fri Jul 31, 2015 4:31 pm

This is an upgrade that just moved up my list.
Northern VA, I-95 drone...
RHD 81 635
02 530i
00 528iT
91 535i

jacko
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Post by jacko » Sun Aug 02, 2015 8:22 pm

Looking like best source in the US is going to be Rockauto for price & warranty.
Jack
Arlington, Texas. USA

1989 635csi
Automatic

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ericono
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Post by ericono » Tue Aug 25, 2015 2:52 am

Anyone else done this? Would like to hear which version of the fan you used (early or later like OP). Would also like to hear how the assembly was mounted.

Also curious to hear any long(er) term reports. Did anyone perform this mod and then ditch their mechanical fan?

Thanks,

Eric
'85 M635, '00 528iT, '98 Z3

jacko
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Post by jacko » Tue Nov 03, 2015 5:55 am

Mounted a stacked pair of PF condensers (16 x 20 ) and the e39 is just a litte bit too big. Have to bend up a sheet metal "funnel" to mount the fan on now.
Jack
Arlington, Texas. USA

1989 635csi
Automatic

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dwcains
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Re: E39 Aux Fan Upgrade How To

Post by dwcains » Mon Aug 21, 2017 6:45 pm

I just picked up a fan from a mid-2000's E46 3-series with an auto trans. 16" fan is very similar to the E39, and has multiple times more air flow than the OEM E24 aux fan.

Image

I'm going to use the original fan speed controls on the car, but will be adding a pair of waterproof 50-amp relays, as the originals in the fuse box are only on 25-amp circuits. I'll post some pics of the relays/resistor setup as soon as it's built. This fan was originally digitally controlled, and I'll remove the fan control module and mount the relays and resistor in its place. Power will be provided thru 10awg wiring.
Dean
Lutz, FL

'85 635 CSi Euro #9402254
'87 Spider Veloce
'92 Spider Veloce
'08 350Z

Image

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sansouci
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Re: E39 Aux Fan Upgrade How To

Post by sansouci » Wed Sep 06, 2017 10:46 pm

Dean,
I'm eager to see how this works....
Sansouci
84 E24 633Csi Auto, Bronzit/PearlBeige 6997510
93 E32 740il M60 Auto, Alpenweis/Ultramarine
60 535i M30 5-speed Green/Beige (crushed)
71 240Z 4-speed White/Blue (rusty & sold)
65 396 Chevelle 4-speed, Marina Blue/Black (stolen)

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dwcains
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Re: E39 Aux Fan Upgrade How To

Post by dwcains » Wed Sep 06, 2017 11:27 pm

sansouci wrote:
Wed Sep 06, 2017 10:46 pm
y
Dean,
I'm eager to see how this works....
I am, too, except I'm in the hospital yet again. The top left corner of the shroud will need a bit of trimming, but only because I have the Classic Auto Air PF condenser, and the inlet and connections are as originala. The fan itself, won't at akk because it needs a digital signal to its control module. But, the fan will run at full speed if you apply voltage acrosss the brush holders, so I'll. Use the original E24 schematic, with improved wire, relays and resistor for 2-speeds.
Dean
Lutz, FL

'85 635 CSi Euro #9402254
'87 Spider Veloce
'92 Spider Veloce
'08 350Z

Image

User avatar
dwcains
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Posts: 1474
Joined: Sun Sep 14, 2014 6:01 am
Location: Lutz, FL

Re: E39 Aux Fan Upgrade How To

Post by dwcains » Thu Sep 07, 2017 1:09 am

sansouci wrote:
Wed Sep 06, 2017 10:46 pm
y
Dean,
I'm eager to see how this works....
I am, too, except I'm in the hospital yet again. The top left corner of the shroud will need a bit of trimming, but only because I have the Classic Auto Air PF condenser, and the Hose connections are as original. The fan itself, won't at all because it needs a digital signal to its control module. But, the fan will run at full speed if you apply voltage acrosss the brush holders, so I'll usew the original E24 schematic, with improved wire, relays and resistor for 2-speeds.
Dean
Lutz, FL

'85 635 CSi Euro #9402254
'87 Spider Veloce
'92 Spider Veloce
'08 350Z

Image

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