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Trying to track down an AirCon fan noise/problem.


Atomic
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Firstly let me describe the noise... It's like a low volume whine you would get get if you was inside a jet plane taxing along ready for takeoff...

It only happens when they heating system has the aircon switched off. If you switch to the economy mode it dissapears very quickly - but not instantaneously. If you switch on the aircon it returns within 2-3 seconds, e.g. the time it probably takes for a component to spin up and the noise work it's way around the system.

Secondly it's erratic, some days it does it, some not... I'd guestimate it happens around 1/3 of the time.

It is also most noticeable at around 1500 rpm in the lower gears. You can some hear it at lower engine revs but it's much quieter. Above 1500 it slowly dissapears, mainly I suspect due to being drowned out by the engine.

It also to some degree changes it's tune with the engine revs - it doesnt for however directly follow the revs - eg it's not twice the frequency at twice the revs.

To me would tend to indicate it's not being caused by an electical fan, albeit high revs do raise the alternator output voltage a little which could have the desired effect.

Any ideas?

Thanks,

Paul.

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Are you able to pin point the location of the noise? Is it comming form the centre of the dash towards the front? if so may be the blower. The only difference between econ mode and normal opperation is the compressor switching off so could it be the pulley clutch mech etc? confused.gif will have a look when I get home 169144-ok.gif

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I think i had the same problem, turned out to be the little electric water pump that pumps the water round when the rest button is pressed. located in the engine bay under the heater matrix cover to the right hand side. You can just see the tops of the motors if you look in. Hope this helps.

Jools

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[ QUOTE ]

It only happens when they heating system has the aircon switched off. If you switch to the economy mode it dissapears very quickly - If you switch on the aircon it returns within 2-3 seconds

[/ QUOTE ]

You have contradicted yourself there, does it make the noise when the aircon is on(not in econ mode) or when it's off(in econ mode)

If it only does it when the aircon is on then I have the same thing, it was also in the 4.2 sport I had a few years back. It made the noise all the time I had the car from around 30k up to 190k miles. The only time you could hear it was when you were in traffic and moving very slowly or stoped. When you pressed the econ button it would stop and likewise when you pressed auto it would come back but take a few seconds to do so.

At times it used to drive me mad(times when I didn't want any music on) I lived with that for ages when I could of had it fixed, dam I knew I should have asked Audi about it.

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  • 3 months later...

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