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RUDDY
Trainee


Joined: 12 Feb 2014
Posts: 63



PostPosted: Tue Jul 10, 2018 11:48 am    Post subject: 986 A/C Noise Reply with quote

Hi guys, for the last month or so I have been trying to find the source of a noise when my aircon is running.

The noise sounds like a dry bearing and seems like its coming from the dash/bulkhead area, strangely it seems to rise and fall with engine revs when coasting along or rolling up to a junction.

So far I have confirmed the rad fans are not the source, I have removed the blower fan and it is fine, no debris in the area below the cabin filter, I have had the a/c system vac’d down and regassed although it didnt appear to have any leaks, the a/c pump works great and the clutch engages etc without issue, I’ve cleaned all the vents and the evaporator with a/c cleaning products.

I have searched the internet and it serms many have had this ‘noise’ without resolution. Mine appears to be getting worse and I’m off to southern germany in it next week.

The noise cannot be heard anywhere except when you are sat in the car.

The noise disappears completely with the a/c turned off

Any pointers ?

Cheers , Paul
 
  
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HSC911
Zolder


Joined: 23 Jul 2014
Posts: 5717
Location: Bedford


PostPosted: Tue Jul 10, 2018 1:58 pm    Post subject: Reply with quote

RUDDY hell frustrated

Hope you get it sorted Grin

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ragpicker
Estoril


Joined: 14 Apr 2013
Posts: 3719
Location: North East England


PostPosted: Tue Jul 10, 2018 2:35 pm    Post subject: Reply with quote

EDIT - didnt read the whole OP thread.

Have you tried removing the engine inspection panel and listening to the a/c compressor bearing?
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986 S - usually in pieces: http://911uk.com/viewtopic.php?t=112626
 
  
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deMort
Zolder


Joined: 21 Mar 2015
Posts: 5520
Location: Brighton


PostPosted: Tue Jul 10, 2018 7:31 pm    Post subject: Reply with quote

Was the noise exactly the same after it had been regassed as low gass causes this noise and turning off the a/c stops it ? basically exactly as you have described is a low gass fault .

Im wondering if its a leak or a possible expansion valve fault ..

Did they put 850 G of gas in it ?

Any chance of a sound clip ?
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RUDDY
Trainee


Joined: 12 Feb 2014
Posts: 63



PostPosted: Tue Jul 10, 2018 8:00 pm    Post subject: Reply with quote

deMort wrote:
Was the noise exactly the same after it had been regassed as low gass causes this noise and turning off the a/c stops it ? basically exactly as you have described is a low gass fault .

Im wondering if its a leak or a possible expansion valve fault ..

Did they put 850 G of gas in it ?

Any chance of a sound clip ?


Hi, yeah 850g in, 720 out and I doubt it ever had an a/c service prior to this.

With the plastic covers off the bulkhead to reveal a/c pipework and expansion valve I cant hear anything untoward, from inside the car it sounds exactly that area.

I should add the a/c temp works great, thermometer infront of vent gets down toward 4 deg, with a laser thermometer down onto the evaporator it was down to -40’s , I thought the evaporator may have been icing causing the expansion valve to go.

Would the expansion valve make a whining bearing sort of noise ?

Would the dryer create noise if blocked ?

Cheers, Paul
 
  
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deMort
Zolder


Joined: 21 Mar 2015
Posts: 5520
Location: Brighton


PostPosted: Wed Jul 11, 2018 7:04 pm    Post subject: Reply with quote

This is a difficult one .. your description is one of low gass .. basically the gass condenses in the wrong place if the pressure isnt correct and causes various noises .. sometimes from the engine area but more normally from the front and n/s .. where the expansion valve is .

Gass is correct so im into guessing from here im afraid .. logically its the expansion valve .. but ive never replaced one of these in 14 years so whilst it could in theory be that it would be pretty dam rare .

A dryer .. again never replaced one for this ..

See if you can get a sound clip of it and post or email ..

De.Mort@virginmedia.com

i might have more ideas after i listen to it .. if it sounds different to a low gass senario then i might be able to come up with something else .

I dont suppose theres a chance of you being anywhere near Brighton ?


just a thought after writeing this .. have a look under the o/s .. none of the pipes are squashed are they ? ie someone has jacked it up in the wrong place and crushed the x2 pipes o/s front to rear .
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