Ac line keeps breaking C5 1.6HDi

[Rosian Drashkov]

Hey guys,
So I recently got an 07 C5 II 1.6Hdi and I bought it a little cheaper from what they go for as it had some work on it and one of things was the A/C was not working. In the initial inspection I noticed that the thiker A/C line going into the compressor was completely torn so I thought that's where the leak is but had in mind that the condenser might also be bad which turned out be the case as it has the dryer attached to it and who knows how long it had been exposed to moisture.
So I replaced the condenser and that pipe I got a welded by a friend of mine who welds these type of AC lines on a daily basis and I had ice cold aircon but that was short lived. When I got it fixed, a weird rattling noise started to sound as I was driving but I thought maybe we didn't get some plastic cover tight enough. Suddenly the rattling noise stopped and I had no AC again. The pressure test showed that the weld had torn a little and the freon had leaked out. I was told that this is caused by the engine mounts having too much vibrations so I replaced them all even though they were not too bad. I got the line welded again with a little brace welded to it to make it stronger and filled the AC again and it was working but then the noise came back. I found where the rattle was coming from (the same AC line on the back of the engine going into the cabin was rattling against the thin one) so I zip-tied some foam pipe insulation to it and it stopped

. I had to travel with this car yesterday and as I was driving the rattling slowly begun to increase and then again it stopped and once again I am left with no AC. The pipe going to the compressor is like laser cut right next to the weld including part of the brace

.
So before I replace the pipe with a new one that might break again, I am seeking any help from you guys as I am not willing to release any more freon (and money) into the atmosphere. Has anyone else faced such a (weird IMO) problem and what dou you think might be causing it. Any help is appreciated.
Cheers.

[aspire_helen]

It is likely that the aluminium pipe has become fatigued over time and vibration, especially if not properly restrained. In addition, welding changes the crystalline structure of the metal locally, usually becoming more brittle. Another alternative to aluminium welding is Alumiweld (and its many competing products) a type of aluminium "soldering" where the original pipe is not actually melted as in traditional welding. Good for fixing a small hole.

A replacement part may be the traditional and dealer's answer. However, the replacement part pipework is usually complex and expensive. Moreover, due to the cars age you may have difficulty sourcing the new Citroen part, which will be expensive (200euros?). There will be used parts on sale online in the EU, maybe 50 to 100 euros. From your photos, it appears to me the pipe you need may be part number 6460LN - item #1 on the attached parts diag (but you need to confirm yourself). Its the low pressure return pipe (the thicker of the two) between the evaporator and compressor.
As a cheaper alternative, if your mate is used to working on aluminium refrigeration pipework, he may be able to splice in a new length of aluminium pipe eg with beadlock fittings. An even wackier solution may be to cut out the offending length of aluminium pipe and replace it with new flexible hose spliced in with hand-crimped ferrule fittings. This is a good solution to replace pipes with complex bends, and the original end couplings are left untouched. In addition, compression and crimped couplings do not need the system to be completely drained as with any hot solution (welding / brazing). Whatever the solution, make sure afterwards the aluminium portion of pipework is securely restrained to the bodywork immediately adjacent to all welds/joints/ferrules.

Regarding welding or brazing refrigerant pipework...the system must be first purged and it is usually recommended to pass inert gas (CO2 or nitrogen) continuously through the pipe being welded. The reason is that burning refrigerants produce carbonyl fluoride (COF2) which is chemically similar to phosgene (the WW1 chemical warfare agent) but even more corrosive. In the event of a vehicle fire, the risk to drivers, passengers and first responders is acceptably low. However, the risk to technicians frequently welding refrigerant pipework is higher. For that reason, cold solutions are preferred eg replace complete pipe, or use compression / crimped couplings.

Regarding the need to replace the drier and oil. Citroen's Mechanics Handbook for my Mk1 C5 defines a "slow" leak and a "fast" leak. Pipe failures like yours would be "fast" leaks.

2/ Slow leak.
- Slow leaks do not lead to oil loss, therefore the same procedure should be followed as if there was no leak at all.
3/ Fast leak.
This type of leak causes both oil loss as well as allowing air to enter the system.
It is therefore necessary to :
- Replace the dryer.
- Drain as much oil as possible (when replacing the faulty component)

[Rosian Drashkov]

Thank you for the detailed response! The pipe that is giving me headaches is actaully part number 4 on the diagram you've attached

and the place it breaks is right where it goes into the compressor. I'm not entirely sure if the cause is worn-out material and I am aware that welding chages the crystalline structure but in my case the way the weld is done is by adding additional material on the cracked area and a brace to strengthen the welded place

. My mechanic was pretty baffled on why this pipe is breaking on the same spot for the third time and he has asked other fellow mechanics if they might know what could be the cause. One of the mechanics told him that he has had the same case and the reason was a missing a bracket (or clamp or idk what exactly) that holds the AC lines steady and it is in the way when you have to replace the timing belt so many mechanics take it out and don't even bother placing it back in. I see I got the three clips holding the pipes, #20 on the diagram, and I had the pipes clamped in. I dont know if there is something else that could be missing so I will have to take a look at my dad's C5 when I go back in town to compare the two cars and see if there are any differences.

[aspire_helen]

Looks like that pipe is partno 6477F0 .

Part No 6477F0

There is no indication of any additional clamp, but I do note that the bend is heavily corrugated at manufacture - possible thin/weak spots? Of course, the flexible hose (not the aluminium pipe) is supposed to absorb the normal movement of the engine, but if the engine movement were excessive the aluminium pipe would likely fracture exactly where yours has, so it may be unrepairable and need replacing.
On my early C5 Mk1, those pipes between the compressor and flexible hoses are steel, not aluminium, and hence unlikely to fatigue. You may have to resort to a new part. Ebay £25.99 GBP in Lithuania.https://www.ebay.co.uk/itm/363854083960 ... SwMWtikews

[Rosian Drashkov]

So I was hoping to write an update in a few months saying that it is all good now but yet again, I have no A/C...
About two weeks ago I replaced that AC line with a brand new one and I went with one of the more expensive options on the market. I made sure I got all of the clips (#20 on the diagram) were securely holding the pipes, replaced all O-rings again and for a third time refilled the AC system. It was all good until today when I went to start the car and didn't hear the compressor click and the 35+ °C outside air was blowing nicely in the cabin. I went to another place where they do car ACs and they pumped it up with air only to find that the brand new AC line has broken on the exact same spot the old one did so now I am sure that it is not due to a weld that may have weakend the crystalline structure... The new AC line has much softer rubber flex part and when installing it there was no tension on the pipe at all.
So back to square one, I dont know what to do now as I dont want to fix it again, spending quite a lot of money for new pipes and freon just to have the new pipe break and the freon to be released in the atmosphere. Any suggestions from you folks would be really appreciated as all the mechanics I know are baffled at this point.

[aspire_helen]

Can you remove the pipe and end fitting (without doing any additional damage to the pipe) and post closeup photos of the fracture surfaces. It may be possible to deduce the fracture mode . How many engine hours do you estimate before the replacement pipe fractured? Does your engine or the ac compressor vibrate excessively? Does the other pipe attached to the compressor (high pressure output part#3) show any signs? If you fit another replacement, is there any way to brace the pipe to the compressor body?

[Rosian Drashkov]

I just took the pipe off the car and left my car into presumably the best car AC repairshop here where they said they will fab an entirely custom made pipe all made from flexible AC hose so we'll see how that will go.
I am not entirely sure how many working hours the engine has had once the AC was fixed but I mainly did highway driving so after some estimated calculations I would say that it has worked for a total of arround 28~32 hours. There is a close up of the fractured new pipe.

Although it is not really visible it is slightly cracked and leaking air out.

[Doo]

I just took the pipe off the car and left my car into presumably the best car AC repairshop here where they said they will fab an entirely custom made pipe all made from flexible AC hose so we'll see how that will go.
I am not entirely sure how many working hours the engine has had once the AC was fixed but I mainly did highway driving so after some estimated calculations I would say that it has worked for a total of arround 28~32 hours. There is a close up of the fractured new pipe.

Although it is not really visible it is slightly cracked and leaking air out.

I just replaced the condenser on two cars, our 2007 C4 Citroen and a friends 2012 Peugeot 3008. I bought our new condenser from Citroen and suggested our friend goes to the same shop as they are a recognised PSA parts shop. I digress.

The reason for my input is the original condenser I was supplied had a hole in it so I took it back. It was silver coloured aluminium. The replacement seemed sturdier and was still alu, but painted black, as was the (identical) one for friends car.

Now the point I am getting to is I had a helluva job persuading the pipe to go into it's port on the condenser, even with the new (supplied) "O" rings! As an aside, I made sure to lubricate both the flange and the "O" rings with silicone grease.

Pushing the pipe into the port took a fair amount of wriggling and a lot of huffing & puffing to twist it gently (you have about 2mm of left/right side to side play due to the threaded fastener) so when it felt as if it was all the way home, it was still showing a gap that I could have put a washer on under the mating face on the flange and the condenser. I decided to slowly & gently tighten the fastening nut and it did finally go all the way home, but not without a slight twist where the nut was pulling down the flange as it is offset. I would have preferred a double sided flange so you could tighten each side in turn to allow equal forces to send it home.

I haven't yet got around to gassing out car as it's still a work in progress (a slight diesel weep, but life getting in the way ) but I plan to use a bottle of gas I bought for the job. A quick hiss then check the pressure and spray soapy solution at each joint to see if I am good to go. We had a small slow leak over two weeks after gassing so I don't plan to spend another £90 to p!ss it away in the wind

Anyway, I thought I'd mention the fact the tightening process seemed to put excessive force on one side of the flange and it is entirely possible this has happened on the OP cars pipe because while you can forgive and old, metal fatigued pipe for cracking, that shouldn't be the case with a new one! Another possibility is perhaps excessive heat is playing a part in this saga! Is there anything blocked or missing? Is perhaps the compressor heating up more than its spec? Which added with the pipe being stressed somehow, is causing all these fractures?

I've been fixing cars for a long time and this is the first time I have seen this in an AC pipe. You see it on PAS pipes which have rusted or brake lines or even coolant pipes. But if an AC line is cracked it's almost always as a result of a frontal impact or someone has put undue stress on the line (pulling the engine or changing a radiator sort of thing).

That is a bit of a head scratcher....

[Rosian Drashkov]

Thanks again for the detailed response!
In my previous response I forgot to mention that the high pressure line (the thiner pipe below the problematic one) is just fine and haven't had any troubles with it.
I see how getting the pipe inserted into the compressor might cause some problems but I made sure that it went in perpendicularly and the O-rings were well lubricated. When I took the pipe off of the car today I inspected the O-rings and they were in good shape (they were not squished or pinched). As I previously said the new pipe went in like it's at home without any tension or stress on it. I had also noted up here somewhere that I got the engine mounts replaced with new ones and the motor was not shaking or vibrating. In terms of heat, I dont know if the compressor gets any hotter than usual being buried down the engine bay and the outside temperatures being over 30°C lately but the weird thing is that this is the "cold" pipe and it really gets freezing cold and sweaty when the AC is running. All of the mechanics that looked at the car are certain that it has not been in a front end collision as everything is looking nice and straight.

[Doo]

Thanks again for the detailed response!
In my previous response I forgot to mention that the high pressure line (the thiner pipe below the problematic one) is just fine and haven't had any troubles with it.
I see how getting the pipe inserted into the compressor might cause some problems but I made sure that it went in perpendicularly and the O-rings were well lubricated. When I took the pipe off of the car today I inspected the O-rings and they were in good shape (they were not squished or pinched). As I previously said the new pipe went in like it's at home without any tension or stress on it. I had also noted up here somewhere that I got the engine mounts replaced with new ones and the motor was not shaking or vibrating. In terms of heat, I dont know if the compressor gets any hotter than usual being buried down the engine bay and the outside temperatures being over 30°C lately but the weird thing is that this is the "cold" pipe and it really gets freezing cold and sweaty when the AC is running. All of the mechanics that looked at the car are certain that it has not been in a front end collision as everything is looking nice and straight.

Cold does make things brittle, but these are supposed to be designed for this kind of stress

I wonder if it ay be worthwhile setting up the pipe then mounting a GoPro camera & light (like an LED from the car battery) and doing a time lapse recording to see if there is anything unusual going on. Too many times to be just bad luck You haven't upset the local cat have you

[Rosian Drashkov]

I wonder if it ay be worthwhile setting up the pipe then mounting a GoPro camera & light (like an LED from the car battery) and doing a time lapse recording to see if there is anything unusual going on. Too many times to be just bad luck You haven't upset the local cat have you

Not that I know of. All the cats in the neighborhood seem to be enjoying it when I'm petting them . Plus I got all my undertrays so they shouldn't be able to get to there .

Anyways I just got the car from the repair shop and that's what they came up with.

. I will place more detailed photos later after the car and the weather cools down a bit. We'll see how long will that thing hold up .

[Doo]

I wonder if it ay be worthwhile setting up the pipe then mounting a GoPro camera & light (like an LED from the car battery) and doing a time lapse recording to see if there is anything unusual going on. Too many times to be just bad luck You haven't upset the local cat have you

Not that I know of. All the cats in the neighborhood seem to be enjoying it when I'm petting them . Plus I got all my undertrays so they shouldn't be able to get to there .

Anyways I just got the car from the repair shop and that's what they came up with. . I will place more detailed photos later after the car and the weather cools down a bit. We'll see how long will that thing hold up .

Nice looking repair. Good luck