Air Conditioning.. Leaks

[pikesrelaybus]

Hi Guys,

So, my 140k mile 3.0l 160ps bus has lost it's ability to cool the inside. This hot weather we're having prompted me to take it to ATS who lobbed they're automated system which showed no problems, 2 weeks later and it's stopped again. They told me that they insert a dye for such situations but when I took it back they couldn't find any leaks. The Nitrogen they pressure tested it with has a gauge which dropped slightly over an hour, they said it was such a small leak it was undetectable but I guess this means they have spent enough time on this and don't want to know. Anyway, question is, is there any weak spots I should look for. I'm tempted to get either a IR torch, have a look at night time or simply pressurizer it and go round with a soapy solution from a spray...

[paul.h]

It is a UV dye that is put in with the gas so you will need a UV torch to spot the dye. Our C5 was regassed a few weeks ago but within a couple of weeks was not cooling that well so I took it back. They have checked it and found the condenser at the front is leaking so will be fixed next week. They also said the compressor looks a bit damp but that can wait and any leaks from it would be small compared to the condenser. They said they have replaced a lot of condensers so must be a common failure. This is at our Citroen dealer, they may be more expensive than elsewhere but they always do a good job so I can trust them.

 

To find a leak you would need to use the torch and check all the pipes, all the joints, the condenser (this could be prone to being hit by stones with it being at the front), the compressor, the evaporator but this may not be that easy to check due to its location. Doing the check in a darkened area might help. If you use soapy water it might wash off any dye at a leak point so it may be best not to do this.

[pikesrelaybus]

The dealership said something along those lines, I'm sure they're thorougher but the multiple visits would make it very costly. They refused to look at the air-con due to another issue and then it also needed a service, so that's two more visits, why they can't do it in one visit I'm unsure but it would help me. I guess they can't tie up the workshop so multiple visits is better for them. However, the engine specialist I'm going to on Wednesday to sort out my engine starting problem said it wouldn't be problem. ATS who re-gassed it looked but I guess they didn't want to put too much time into it as they'd not be able to repair it. The chap did say mind, once I get it fixed come back and they'd re-gas it (wink wink), I guess either free or a good discount. My C3's condenser also failed (a long time ago), Because it's aluminum it had got rot in it, soon as it was moved, it simply broke off. I could see the green Dye, very obvious where it had leaked. I note what you say about using soapy water but I was going to pressurize the system and look for bubbles but my first plan of attack is using UV torch.. (or at least, let the specialist have a look!!)

[pikesrelaybus]

So, today I went to a Diesel Specialist to sort my starting issue and he had a look at my air-con. They too could not find any leaks with the UV and after 30 minutes his gauge hadn't moved. He injected some oil which will help seal things but also came up with some stuff made by Wurth, "AC leakage stop plus", hopefully that and his oil plus a recharge will sort it out. It was about 6-8 months before I actually did something about my air-con, spurred on by the hot weather. Interestingly, my electronics to control the air-con is fully automatic, I guess you call it climate control. With the system in automatic I remember if you cranked the temperature up the AC pump would stop. I only found this out when it was particularly cold and even on "HI" it wasn't really warming me up. When I dis-engaged the AC pump, which I thought would have turned off anyway, it got a whole lot hotter. It's not a big deal but I don't remember it behaving in this "always on" when I first got the vehicle. It would be interesting if anyone with the same climate control, circa 2008 is able to turn the AC pump on/off simply by turning up the temperature... But, I'm rather hopeful the specialists will sort this out too..

[paul.h]

Our 2007 C5 has climate control but I do not use it in auto. I have just checked it and when not in auto, if the temp is set to HI, the compressor still runs all the time if it is set to be activated. I have tried it in Auto and HI but could not really tell if the compressor was switched off - it was 30°C outside though so that may have had an effect. The car handbook does not say if the compressor is stopped in auto if set at HI. If  I remember, when it cools down in a few days I will check it again.

[paul.h]

I have tried again on our C5 to see if the air con compressor automatically stops when the temperature is set to HIGH and it does not, even if the temperature button is pressed to increase the temperature. However, when not on Auto, if set to LOW and the temperature button is pressed twice to reduce the setting, it automatically starts the compressor. To stop the compressor again I have to go in to the Menu otherwise it stays on.

[coastline taxis]

depending on the year of the bus. some of the newer models you need to go into climate control menu and link the air con to the heating system so it turns on and off with the temperature settings

[pikesrelaybus]

Thanks for your reply. It's a 2008 model and I've had it from new. I noticed (as I learned how it worked) that the compressor would only engage if there was a cooling demand. Basically in FULL AUTO you can only adjust the temperature and in doing so I could hear the compressor clutch cutting in/out. If you adjust any other settings, air direction etc then the FULL part goes and it remains in AUTO. Having said that, one winter coming back from London I was cold and it didn't matter how high I set the temperature I couldn't get warm. It was only while playing about with it I switched off the AIR-CON by the dedicated frost icon button, then the warmth came, so it was basically on cooling away even when set to max. It was a pity I only discovered this at the end of the journey, not the start cos I was cold!..

 

So, what did the specialist do to the system, well he attached his automated gassing machine, it pressure tested the system fine, because I indicated issues he left it good hour and there was no drop. He then some AC-leak stop stuff, forgotten what make it was but it wasn't cheap, before re-gassing. It lasted 4 days. It's booked in again for this coming Monday but it might help if there was some locations I could point out for them to torch for the dye. I think the pressure of the compressor is pushing it past a leak in the hi side, like the compressor output or the evaporator. The pump is obvious to find but how do you look at the evaporator? getting a bit expensive now, 2 recharges, this magic stuff and a few hours has resulted in 3 weeks cooling. The first time it was recharged it lasted 2 weeks, the second time way less, even with the stop-leak stuff in the system.

[paul.h]

Possibly if the evaporator is leaking, the dye might run down and out of the drain along with the water that condenses on the outside of the evaporator. The drain is usually somewhere under the driver's footwell so it could be checked with the UV light. The cabin air vents could also be checked to see if there are traces of dye.

 

If the evaporator does need replacing it looks as if the dash has to be removed. It is around 8 hours total so expensive on labour if you have to pay somebody to do the work.

[pikesrelaybus]

So, I took this info with me to the garage this morning who spent over three hours hunting for any traces of dye or an indication on his electric nose. For 2 hours the system retained it's pre-charge of nitrogen while he disturbed and waggled everything & anything to do with the AC system. There were no traces of dye anywhere and the only indication was the bottom right of the condenser which looks slightly beat up but as he said, a leak there would almost certainly be obvious, so put it down to false indication off his sniffer. So, far it was initially recharged which lasted 2 weeks, the last recharge lasted 5 days if that so there's a leak somewhere well hidden away. The latter included a bottle of Wurth stop AC. I've spent best part of £200 so an 8 hour investigation doesn't fill me with joy, especially since there's no clear evidence the evaporator has failed. It's a complete mystery but I've given up spending any more on the AC, just wind the window down. Fare play to the diesel specialists, he had a damn good look and is mystified at the results, clearly there's a leak but the nitrogen pressure test doesn't show any drop in pressure even after 2 hours.

[pikesrelaybus]

Forgot to mention, we couldn't find the AC dryer, I thought it was the metal coil behind the front bumper but the pipes don't go there. I believe it has one as you can get the part on eBay. Just couldn't find it. I've just ordered a torch but to be fair, I believe I'm not going to find anything the chap in the garage, unless I start digging deeper than he did.

[paul.h]

According to the parts diagrams the AC dryer is a cartridge that is under a cap at one end of the condenser. On vehicles with an extra condenser and fans on the roof there is also a separate dryer there. You can see the parts diagrams if you register on service.citroen as an other professional non emergency services and as a member of the Citroen Owners Club. Use your VIN (VIS) to left once on to find your vehicle and the air conditioning can be found under Electric Unit, Comfort and Convenience http://service.citroen.com/do/changerParametres - you might need to select your language first. You do not pay to see the parts diagrams but you can pay to see the workshop manual procedures.

 

If you look at the diagrams it might help suggest where there might be a leak such as seals or maybe the relief valve. For the pressure to remain for a few days though any leak will be small. As well as the dye some of the oil might leak out so you could look for that but it will probably be colourless oil.

 

When the air con is running, some parts get hot, others cold, the oil is circulated and the compressor turns - these may change the leak rate when compared to a nitrogen pressure test.