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Discussion Starter · #1 ·
Dear All,

The A/C intercooler fan doesn’t seem to work anymore on my 740d.
I tried to use ICOM and INPA/ISTA-D but it won’t move at all.
Error codes I got following the clear-codes and actuation were the following ones in DDE :
  • 41F1
  • 4B22

I tried to use a multimeter and oscilloscope to test/probe the signals : +12V, GND and PWM.
They are all good, but still fan isn’t spinning at all.

As I’m pretty sure the error codes and the 340000Km combined the fan is done and needs to be replaced, I went to check the parts references and what was my surprise when I saw that the whole fan assembly is something around 1000€ …

I’m sure the fan can be found without the whole assembly, and I was wondering if any of you already went the same way/path.

Do you have any idea of what could be the right part ref for an aftermarket fan that goes in place ?
There are only 3 screws to detach the actual one from the assembly but seems like BMW doesn’t sell the fan only.

Thanks
 

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I'll tell you something funny. I spent hours researching the same thing when I discovered my fan had died. I don't know if yours will be the same fan, but for mine I found the fan motor was the same as what's used on some e53 X5s and some L322 range rovers, however the fan blade and shrowd is different.

What I ended up doing was taking the motor out of the fan assembly for an L332 and attaching my fan blade and screwing that to my fan shroud. Only you will know if it's the same motor as yours so look at some listings and photos to compare.

To be fair though this might not work out too cheap for you depending on availability of second hand range rover parts, I'm in the UK so got the fan for £25 delivered!
 

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Discussion Starter · #3 ·
I'll tell you something funny. I spent hours researching the same thing when I discovered my fan had died. I don't know if yours will be the same fan, but for mine I found the fan motor was the same as what's used on some e53 X5s and some L322 range rovers, however the fan blade and shrowd is different.

What I ended up doing was taking the motor out of the fan assembly for an L332 and attaching my fan blade and screwing that to my fan shroud. Only you will know if it's the same motor as yours so look at some listings and photos to compare.

To be fair though this might not work out too cheap for you depending on availability of second hand range rover parts, I'm in the UK so got the fan for £25 delivered!
Hello and thanks for your answer, Greatly appreciated !
Do you have a diesel E65 version too ? I know that 730d and 740d have the same A/C fan but petrol engines do not seem to share the same part ref.
 

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It's an e66 760Li I've got but I believe it used a different setup to most petrols with a viscous fan and an electric one.

To be honest I didn't go off part numbers just by looks as I couldn't find anything confirming if it was the same motor. In any case I should say that the plug for the motor is different on the e53/L322 so you'll need to either splice in the old plug or install a new one.

I'd just get yourself down your local breakers and see if the fans either of those models looks like your own. The only ones my local breakers had were from fires but I was still able to see it was the same and order one off evilBay.
 

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Discussion Starter · #6 ·
Hey, so at the end of the day, I went for a used BMW 5 E53 3.0D fan only (without casing).
Part reference is this one > 64546921382
I measured the one I have which is a 438mm diameter inside a 450mm casing > These informations corresponds to the model I bought on evilBay here : BMW X5 Series E53 M57 3.0d Engine Cooling Radiator Shroud Fan Motor 6921323
The reference of this fan is a little different as part number has been superceeded since then as the item description indicates :
BMW X5 Series E53 M57 3.0d Engine Cooling Radiator Shroud Fan Motor 6921323 with broken plug, please see photos
Genuine used OEM part
Part no: 64546921382
Part Replaces: 64546919052 64548386085
This one was very cheap because connector (which is not the one I need of course) is broken but this is definitely not a problem as I will put the one from my dead fan on it.

Crossing fingers for everything to work smoothly after that // Anyway I'll report back here once I will do the job.
 

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That definitely looks like the same motor to me. Even if the fan blade is a different size to yours, you can remove the one that came with that one and install your own one. Just immobilise the motor using the 15(?)mm hex in the centre and rotate the fan disc clockwise (I think) and it should turn like 1/3 of a turn and lift off. New/old one installs the opposite way.

Happy someone has documented part numbers, something I stupidly didn't do.
 

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Discussion Starter · #8 · (Edited)
Hello @Thepowerfulpotato ,
I’ve just received the used fan from the E53.
I just have a little question as I want to test it before putting it inside my E65 …
What should be the positive/negative wire colors based on the attached photo ?
I would say :
  • BROWN: Ground (as usual ?)
  • BLUE : +12v
  • BLACK (small) : PWM

Am I correct ?
Automotive tire Motor vehicle Fender Gas Rim
 

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Oh now that's a good question I can't remember to be honest. I'll check mine when I get home. What you say makes sense but I also work on forklifts where brown is used as the ground so could be either.

Bear in mind the fan won't spin without the PWM signal so use ista/inpa to test it. Also be careful as if it spins up without being bolted down it could cause some damage!
 

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Discussion Starter · #11 · (Edited)
Oh now that's a good question I can't remember to be honest. I'll check mine when I get home. What you say makes sense but I also work on forklifts where brown is used as the ground so could be either.

Bear in mind the fan won't spin without the PWM signal so use ista/inpa to test it. Also be careful as if it spins up without being bolted down it could cause some damage!
I've edited my post so BROWN == GROUND which seems logical to be honest.
I know that PWM is needed, so I'll use an arbitrary waveform generator to produce it.

Last question : do we assume that FAN takes +12v and GROUND ... but what goes for PWM signal ? +5v ... +12v ?

======================== EDIT ========================
I think I managed to get the information in a YouTube video : BMW X5 Electric Fan Repair
As we can see in this part of the video (8m28s), we have a 5v signal with a frequency of 100kHz.
Rectangle Font Gas Computer Gadget


Based on that, I'm sure that fan speed is modified by narrowing/expanding the duty cycle of the signal.

I'm going to do some tests with my lab power supply and arbitrary waveform generator now I have all the needed informations.
Hopefully ... BROWN is GROUND because if it is not ... KABOOOOM !!! :ROFLMAO:


+++ a very good post on electronical aspects of fan and the signals around : DIY: Troubleshooting Radiator Electric Fan
 

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Discussion Starter · #12 · (Edited)
One wonderful video with all the required informations to run a fan on a table without the car being close : BMW AUX Fan test

So at the end of the day, here are the correct and definitive instructions for BMW PWM fans with 3 wires :
  • BROWN : Ground
  • BLUE : +12v
    • Use a battery or a power supply that can deliver 50A
    • Pay attention to this as these fans can easily draw between 400-600 watts (depending model)
    • So prepare a correct power source ; for example 500 watts with 12volts already gives a current of 42A !!!!! > P=UxI
  • BLACK (small) : PWM
    • Amplitude/Voltage : 12v
    • PWM frequency : 160Hz
    • Duty cycle : 50% (50% == 50% of fan speed ... 100% == 100% of fan speed)
WARNING : When powering these fans, as they can handle big currents, they will move respectively which means if you don't secure them on something heavy to avoid them rotating freely, you will face disaster situation.
You have been warned (I did not at first try, but hopefully I stoped just when the fan was starting so nothing bad happened).



That's pretty much it, hope that helps !

On my side, I could verify that the used fan I bought is 100% working before inserting it in the car.
Next step : puting the fan in the car :ROFLMAO:
 

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Discussion Starter · #14 ·
Did the work right now.

What to say ... hum ... well :
  • Had to extend the cable from the replacement fan
    • Length was 40cm and genuine E65 was 60cm
  • Had to switch the fan wing circle between fans
    • Cable on replacement fan was 46cm diameter and genuine was 42cm
    • NB : This was the hardest thing to do >>> such a pain in the 455 to dismount because everything was rusty ! Even the 3 screws were locked, I had to use a lot of WD40 and patience
  • Packed everything up back again in the car, used ISTA-D and triggered "Electric fan activation" from DDE : SUCCESS !

Cheers !
 
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