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Discussion Starter #1
Hi,

I've noticed that my electrical fan in front of the AC condenser doesn't run simultaneously with the AC compressor, which i believe it should do?

My condenser was changed (and the system regassed with R134 - it's a -94 model) this spring due to a gas leakage and the AC performs very well. At 20-25°C outside it is so cool that I'm freezing and can turn it off periodically.

I'm almost sure that the aux fan did kick in once when my viscous fan coupling was slipping (which was fixed immediately) and the aux fan can easily be turned by hand, so it's not stuck.

I've read here that the fan is regulated by an AC pressure sensor to run when the compressor is running. Is this sensor somewhat accessible? Any help with troubleshooting this issue and testing the fan is greatly appreciated.
 

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I think the aux. fan starts when the condensor needs to be cooled. I don't think it runs all the time that the A/C is on. That indicates that the fan does not have to be engaged if you are driving at there is sufficient cooling from the wind.
My aux. fan only runs if it hot and the car isn't making much speed.
 

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Mr. J said:
Hi,

I've noticed that my electrical fan in front of the AC condenser doesn't run simultaneously with the AC compressor, which i believe it should do?

My condenser was changed (and the system regassed with R134 - it's a -94 model) this spring due to a gas leakage and the AC performs very well. At 20-25°C outside it is so cool that I'm freezing and can turn it off periodically.

I'm almost sure that the aux fan did kick in once when my viscous fan coupling was slipping (which was fixed immediately) and the aux fan can easily be turned by hand, so it's not stuck.

I've read here that the fan is regulated by an AC pressure sensor to run when the compressor is running. Is this sensor somewhat accessible? Any help with troubleshooting this issue and testing the fan is greatly appreciated.
The aux. fan should run at low power whenever the aircon is on to cool the condenser. The resistor on the fan commonly fails, resulting in the fan only running on full power when the engine gets hot enough. It's pretty easy to replace the resistor but you'll need to remove the front bumper.

Regards

Alex
 

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AlexA said:
The resistor on the fan commonly fails, resulting in the fan only running on full power when the engine gets hot enough. It's pretty easy to replace the resistor but you'll need to remove the front bumper.
And it costs all of €16,-. I wish it was just my resistor that's shot, but unfortunately so is my fan. The rediculously expensive piece of ......
 

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Discussion Starter #5 (Edited)
Sorry to hear Stevie. Hope that my fan is still ok...



Hmm, sounds like I have to figure out how to remove the bumper then... :3: Where is the resistor mounted - can it be seen with the bumper in place so I can ensure that everything is properly connected as a first check?

Thank you all for helping, this board is great! :cheers:
 

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Mr. J said:
Hmm, sounds like I have to figure out how to remove the bumper then... :3: Where is the resistor mounted - can it be seen with the bumper in place so I can ensure that everything is properly connected as a first check?

Thank you all for helping, this board is great! :cheers:
The resistor is the little rectangular thingie on top of the electric fan....
http://www.realoem.com/bmw/partgrp.do?model=HE51&mospid=47384&hg=64&fg=55
 

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Oh, sorry, that was based om my VIN (540i), here's one for the M5:

http://www.realoem.com/bmw/showparts.do?model=HD91&mospid=47385&btnr=64_0132&hg=64&fg=55

Same pic. though, just different model (HD91)......

And it's much easier to pop out the grill to reach the resistor. Let me look up the instructions....

Edit: Here you go: pop out the grill and leave the front bumper on. Much easier. Don't know if you can remove the fan through here though, but in your case that shouldn't be neccesary.

http://digest.net/bmw/archive/v5/msg02119.html

BTW, if the resistor is shot the fuse in the fusebox is probably blown too. The aux-fan has its own fuse, nr. is on the inside of the lid.
 

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Hi!
I have just dismantled the fan and if you`re doing this, the bumper has to come of, AND the grille AND a light horizontal beam in front of the fan. If you are just going to change the resistor, the bumper has to be removed as the resistor is situated on the edge of the lower part of the fan assembly, right hand side seen from the front.You can see it through the air intake holes in the bumper.
By the way I can`t really see how the grille could be popped out without taking out the bumper, as the lower plastic screws for the grille are hidden behind the body coloured metal panel between bumper and grille. To remove this you have to take out the bumper.
Removing bumper is easy, you just remove the black bumper strips (start bending them out at the reg. plate (there is a "crack" there) with a screwdriver) when the strip is removed, you can see four 17mm nuts that have to be removed. After this you just pull out the bumper (carefully so that you don`t rip of the leads to fog lights and temp sensor, there is enough play in those that they can be disconnected when the bumper is off, but held close to the front)
Now you have free access to the resistor.

:M5thumbs:
Sakke
 

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Discussion Starter #10 (Edited)
DrSakke said:
Hi!
I have just dismantled the fan and if you`re doing this, the bumper has to come of, AND the grille AND a light horizontal beam in front of the fan. If you are just going to change the resistor, the bumper has to be removed as the resistor is situated on the edge of the lower part of the fan assembly, right hand side seen from the front.You can see it through the air intake holes in the bumper.
By the way I can`t really see how the grille could be popped out without taking out the bumper, as the lower plastic screws for the grille are hidden behind the body coloured metal panel between bumper and grille. To remove this you have to take out the bumper.
Removing bumper is easy, you just remove the black bumper strips (start bending them out at the reg. plate (there is a "crack" there) with a screwdriver) when the strip is removed, you can see four 17mm nuts that have to be removed. After this you just pull out the bumper (carefully so that you don`t rip of the leads to fog lights and temp sensor, there is enough play in those that they can be disconnected when the bumper is off, but held close to the front)
Now you have free access to the resistor.

:M5thumbs:
Sakke
Hi,

I had a look at the resistor this weekend and also found out that it's situated at the lower part of the fan assembly, behind the bumper. My first attempt was to give it a good spray with anti-corrosion/contact aid (well worth a try since it cured a temp sensor showing -37 in September! :M5thumbs: ) called 5-56 (the equivalent of WD-40 I believe). Haven't really tested it yet since the car's been resting and the weather isn't so warm and nice either. But since I'm going to BMW tomorrow to have two new tyres fitted I'll ask them if they can have a look at it. I hope it's just the resistor...
Thank's for helping, good to know what to expect in case I end up on the garage floor. :)
 
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