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heed
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Joined: 24 Jan 2019
Posts: 64



PostPosted: Mon Sep 02, 2019 8:32 pm    Post subject: Slowest AC Leak..... In the world Reply with quote

Well, maybe the title isn't strictly true, but I have a pretty slow leak.

When I bought the car there was no gas in the system (usual cabin sounds, warm air, De Mort tells me no gas etc)..

So I took it to Pro Tyre who did the whole vacuum, drain, fill. Ice cold air Smile

This was about 3 months ago. Over the last couple of weeks the system has got chatty in the cabin and now I'm sure it's basically all gone. The air blows the same temp with/without AC and it's super noisy when AC is on.

Question: since I'm guessing this is a super slow leak, where would one start looking for clues? Any tips? I'd rather have a poke around myself initially even if it's just to help point a specialist in the right direction. Are there any dye kits that are reasonable value for money for a one-off hunt?

At least this has happened in September rather than May.
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maldren
Suzuka


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PostPosted: Mon Sep 02, 2019 9:02 pm    Post subject: Reply with quote

Mine took some time to leak away with a damaged pipe by the LHR jacking point and, yes, the pump was noisy as a result.
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2003 996.2 C2 Coupe Arctic Silver
 
  
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easternjets
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Joined: 29 Apr 2016
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PostPosted: Mon Sep 02, 2019 9:12 pm    Post subject: Reply with quote

More than likely a condenser, they do get a pummelin from chippings
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Alex
Le Mans
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Joined: 06 Mar 2014
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Location: The Ribble Valley, Lancashire

2000 Porsche 996 Carrera 4

PostPosted: Mon Sep 02, 2019 9:38 pm    Post subject: Reply with quote

As above, although once these cars hit around 15 years old the long pipe down the length of the car becomes perforated (if it hasn't already been damaged round the jacking point). You can tell by looking at the condensers if its those or not. Same goes for the long pipe under close inspection.
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easternjets
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PostPosted: Tue Sep 03, 2019 9:03 am    Post subject: Reply with quote

If you have the eqpt then the front bumper is quite easily removed, it does require wheels off and being jacked up onto axle stands but you will have good access to the condensers and be able to see if they're past they're best.
You will also be able to clean all the crud out which will amaze you how much comes out.
If you search the net you will find a step by step guide on removing the plastic bumper cover, takes about an hour the first time.
Design 911 do replacement condensers which I believe are OEM or you can buy cheap copies for under a £100.
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Alex
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PostPosted: Tue Sep 03, 2019 9:18 am    Post subject: Reply with quote

I did mine on my ramps on the drive without removing the wheels (incase you dont't have axle stands).
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maldren
Suzuka


Joined: 07 Oct 2016
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PostPosted: Tue Sep 03, 2019 9:58 am    Post subject: Reply with quote

Alex wrote:
I did mine on my ramps on the drive without removing the wheels (incase you dont't have axle stands).


IIRC I did mine on the ground but I jacked up the car to take off the wheel arch liners.

If you've not done it before, fit mesh guards while you're at it. It's all pretty easy DIY (although one of the screws attaching the bumper to the front wing inside the wheel arch was a bu**er to remove first time round.)

I bought condensors via the internet from a specialist A/C firm, cheaper than D911 at £142 a pair including 'O' rings and I suspect that you can get them cheaper than that.
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cvega
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Joined: 25 Feb 2013
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PostPosted: Tue Sep 03, 2019 10:37 am    Post subject: Reply with quote

i have a slow leak from the joint where AC pipes pass under the passenger door. condensers brand new.
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deckster
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Joined: 12 Jul 2015
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PostPosted: Tue Sep 03, 2019 11:46 am    Post subject: Reply with quote

I finally traced my slow leak to the long pipes running under the car. Well, I say 'I', I mean the air conditioning specialist that I got in. Three separate garages totally failed to identify the source of the leak whereas this guy turned up at my house, gassed the system, waved a detector around and pinpointed exactly where it was within 10 minutes. Should have got the professionals in years ago as ever since the pipes were replaced it it's been beautifully cold and quiet.
 
  
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911munKy
Montreal


Joined: 26 Nov 2014
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PostPosted: Tue Sep 03, 2019 3:27 pm    Post subject: Reply with quote

Mine also had a slow leak, I had the a/c cleaned and refilled but within 3 weeks it wasn’t blowing cold and the pump was rubbling. The condensers looked ok but I noticed a dent in the pipe by the front RHS jacking point, it didn’t look like there was a crack but I covered the dent with JB Weld. Next Summer I had the a/c refilled again and it has been working fine ever since.
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wasz
Sepang


Joined: 28 Dec 2012
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1999 Porsche 996 Carrera 2

PostPosted: Tue Sep 03, 2019 3:39 pm    Post subject: Reply with quote

911munKy wrote:
Mine also had a slow leak, I had the a/c cleaned and refilled but within 3 weeks it wasn’t blowing cold and the pump was rubbling. The condensers looked ok but I noticed a dent in the pipe by the front RHS jacking point, it didn’t look like there was a crack but I covered the dent with JB Weld. Next Summer I had the a/c refilled again and it has been working fine ever since.


Common for tyre fitters to wang a jack under without looking, the pipes are almost as low as the jacking point.

The long pipe is a bit of a faff to fit but I did mine on the driveway. I cut it in half afterwards and you can see the corrosion going on in there.

As the lowest point in the system any water collects there and the pipe rots.

Just a reminder that to knowingly vent refrigerant into the atmosphere is a criminal offence, because of the damage it does. If you know its leaking or likely to leak then get it fixed properly!
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Alex
Le Mans
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Joined: 06 Mar 2014
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Location: The Ribble Valley, Lancashire

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PostPosted: Tue Sep 03, 2019 3:46 pm    Post subject: Reply with quote

wasz wrote:

Just a reminder that to knowingly vent refrigerant into the atmosphere is a criminal offence, because of the damage it does. If you know its leaking or likely to leak then get it fixed properly!


+1.
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911munKy
Montreal


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PostPosted: Tue Sep 03, 2019 4:36 pm    Post subject: Reply with quote

^
The problem is that with a slow leak it is difficult to tell as when the garage does a pressure test before filling up it passes with flying colours, it is usually only weeks afterwards when the a/c stops blowing cold that you realise that the problem in the first place was that you still have a leak after a repair.
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deckster
Newbie


Joined: 12 Jul 2015
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PostPosted: Tue Sep 03, 2019 5:06 pm    Post subject: Reply with quote

911munKy wrote:
^
The problem is that with a slow leak it is difficult to tell as when the garage does a pressure test before filling up it passes with flying colours, it is usually only weeks afterwards when the a/c stops blowing cold that you realise that the problem in the first place was that you still have a leak after a repair.


Totally agreed, and my firm conclusion is that these pressure tests aren't worth a damn.

In my case I asked the air con chap to come along at the time that I had the pipes replaced and do a retest there and then - he identified a further slight leak at one of the seals which was fixed on the spot. Well worth the extra few quid for his time.
 
  
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Alex
Le Mans
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Location: The Ribble Valley, Lancashire

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PostPosted: Tue Sep 03, 2019 5:54 pm    Post subject: Reply with quote

deckster wrote:
911munKy wrote:

The problem is that with a slow leak it is difficult to tell as when the garage does a pressure test before filling up it passes with flying colours


Totally agreed, and my firm conclusion is that these pressure tests aren't worth a damn.


Lets not get confused here. There's two types of tests garages use:

1. The standard vac down process that an 'all-in-one' machine does when going through the aircon service process. If the machine isn't able to vac the system down then it will inform the user there is a leak. This way will only detect major leaks like heavily perforated condensers or a split pipe, etc.

Here: https://www.launchtech.co.uk/air-con-machines-and-packages/eck-1090-ac-service-station/

2. Nitrogen air-con leak detection kit. This fills the system with Nitrogen and is able to put the system under intense pressure much higher than in normal operation. Once the system is under intense pressure, leaks can be easily found (or heard in my case). This way can be left under intense pressure until and monitored until the user is happy the system is leak free. This is the only way to do a proper test as all the first option is doing is informing the user the machine can not vac down the system. Many garages use this Nitrogen kit to detect leaks.

Here: https://www.prosol.co.uk/product/air-con-leak-testing-nitrogen-pressure/
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deMort
Dijon


Joined: 21 Mar 2015
Posts: 7183
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PostPosted: Tue Sep 03, 2019 6:57 pm    Post subject: Reply with quote

I do both of what Alex has said depending on the situation .. a nitrogen test takes time so its an agreed extra charge .

The machine will find some leaks .. you have to run it for longer than the default settings and you also need to know the model of car pretty well .. the difference between 1mb loss and 3 mb loss is about 3-4 months till a low gas situation .. if tested over 10 mins .

Start getting 8 mb loss and its 3 weeks on these cars .. that is a very small loss and the machine won't throw up a problem .. the mechanic is the one who should see this .

nitrogen is used when we know there is a leak .. we are not allowed by law to regas the car in this state .. big fines etc .

It's an over pressure and we look , listen and use soapy water on all the pipes we can to find the leak.

Often it's a pipe inside a clamp support that is the area of leak .. water ingress over years and a nice rubber bush to hold it there .

Most machines have an auto dye setting so it will inject dye regardless .. unless the mechanic switches it off so there should be the usual green lumiose dye in the system .. even if not .. any oil patch on an a/c pipe is a leak .
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heed
Trainee


Joined: 24 Jan 2019
Posts: 64



PostPosted: Thu Sep 05, 2019 9:42 pm    Post subject: Reply with quote

Sorry for the late reply. This thread has some great replies in it, thanks!

The condensers on my car have already been replaced (well, 5 years ago so I suppose not that new). Plus I have a mesh fitted on the front bumper.

Given that, I’m going to first see if I can spot anything obvious on the pipes, and will check near jacking points.

Thanks all!
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