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Discussion Starter · #1 ·
Hi, I've read the issues that people have had with mk4 fans but I was wondering if anyone has had the problem I am with my mk5:

The fans come on full blast from cold start and never go off.

Anyone got any idea what the problem might be?

The car heats up to 90 like normal and there are no other problems that I can see, just the fact the fan is always on full blast no matter what
 

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Not heard of many issues with fans on the MK5 like the MK4.

On cold start are you sure it's the fans you hear and not the secondary air pump as it's quite loud.?

If it's the fans coming on full blast then you have an issue as they should only come on full speed above circa 105 degrees coolant temp. They do rotate half speed if on auto (ac on) but they are almost silent.
 
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Discussion Starter · #4 ·
I used to drive with the AC on but I think my AC has stopped working so i've stopped using it til I get it checked out.

Here is a video of it from cold start and you can hear the noise I am meaning, this loud fan noise is constant and never stops no matter what the conditions are


and another video with the climate control turned off completely (No change in noise)

 

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Sorry don't have sound on this PC but I take it you can actually see the fans running on high speed?

Assuming they are it could be a faulty sensor or fan controller.

Either way it needs to be investigated.

You don't want to have the fans running constanly on high speed as there is a risk they may blow a fuse, meaning the fans won't be available when needed and thus risking overheating.
 

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Discussion Starter · #6 ·
Sorry about filming portrait instead of landscape, it looked good on my phone but obviously turns out as a crap crop once uploaded!
 

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Discussion Starter · #7 ·
Sorry don't have sound on this PC but I take it you can actually see the fans running on high speed?

Assuming they are it could be a faulty sensor or fan controller.

Either way it needs to be investigated.

You don't want to have the fans running constanly on high speed as there is a risk they may blow a fuse, meaning the fans won't be available when needed and thus risking overheating.
I cant actually see in because it is so tight but with the noise coming off of the fans i'd say it is on high speed.
I'm going to get it plugged into VAGCOM in a couple of hours time and see if it flags up any faults.

Any idea how i'd go about investigating a faulty sensor or fan controller ?
 

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I cant actually see in because it is so tight but with the noise coming off of the fans i'd say it is on high speed.
I'm going to get it plugged into VAGCOM in a couple of hours time and see if it flags up any faults.

Any idea how i'd go about investigating a faulty sensor or fan controller ?
I'm not sure what you can pick up on vagcom in this area, but otherwise you need to look at the signals in conjunction with the wiring diagram and check they are all as expected going into the fan controller. With the MK5 I'm not sure if the fan controller is still within the fans or external.

SI-R32 may be able to assist you with a wiring diagram.
 

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Discussion Starter · #9 ·
I'm not sure what you can pick up on vagcom in this area, but otherwise you need to look at the signals in conjunction with the wiring diagram and check they are all as expected going into the fan controller. With the MK5 I'm not sure if the fan controller is still within the fans or external.

SI-R32 may be able to assist you with a wiring diagram.
Thanks for your help,

I'll try and contact SI-R32 for the wiring diagram,

Cheers!
 

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Discussion Starter · #10 ·
Had another look at it today....
Both fans - the small (a/c fan i believe) and the big radiator cooling fan - are spinning on full bore tornado mode.
I believe there is on the OFF and Tornado mode options on these fans and they dont run at different speeds, just off and on.

Mk5 GTI's have a common fault of the small fan stopping working on 07 and 08 models and the big fan going tornado mode to make up for it not working.
A small fan replacement fixes this.
Both of mine are spinning so I dont think it is this.

I've messaged Si-R32 to see if he has any diagrams or info on how the fan and cooling system works and what sensors and switches there are.

Does anyone know if there is a fuse I can pull to stop my fans going?
I dont need them as i'm never in traffic and my engine never gets too hot - also its winter now so I'd rather use the car with the fans off for now instead of burning out the fan motors til I find out what the problem is and get it fixed.

Thanks again
Andrew
 

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Did you ever sort this? I have the same issue, fans running when cold, sometimes even when the key isn't in the ignition they come on! Changed Coolant temp sensor and both fans.. no fault codes
 
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