Slowest AC Leak..... In the world

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 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.

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.

More than likely a condenser, they do get a pummelin from chippings

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.

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.

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.

i have a slow leak from the joint where AC pipes pass under the passenger door. condensers brand new.

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.

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!

+1.

^ 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.

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/