Page 1 of 1

Aircon leak from high pressure pipework

Posted: Tue Jun 25, 2019 12:17 pm
by jasimog
Aircon failure last week with VCDS fault code 00229 low pressure. My trusted local aircon technician located a pinhole leak on the high pressure (smaller bore) pipework right underneath the fuel filter. All other functionals inc compressor tested OK.

I'm looking to replace that pipe run from the bulkhead to the condenser, followed by a recharge. I'll post updates here with any tips. Just ordered a new pipe for £45 plus postage (3C0 820 741 AJ).

Re: Aircon leak from high pressure pipework

Posted: Tue Jun 25, 2019 3:58 pm
by maclee
Replacing that pipe will open up the entire system to atmosphere.

In view of this, I respectfully suggest that it would be wise to also replace the dryer, (item 2 on the diagram).

I think the part number you will need is probably 3C0898191, but check with your dealer first.


ac.png

Re: Aircon leak from high pressure pipework

Posted: Tue Jun 25, 2019 8:50 pm
by jasimog
maclee wrote:
Tue Jun 25, 2019 3:58 pm
Replacing that pipe will open up the entire system to atmosphere.
I appreciate the advice, but wouldn’t that apply if any aircon component is swapped out?

Re: Aircon leak from high pressure pipework

Posted: Tue Jun 25, 2019 9:36 pm
by DMitch16
jasimog wrote:
Tue Jun 25, 2019 8:50 pm
maclee wrote:
Tue Jun 25, 2019 3:58 pm
Replacing that pipe will open up the entire system to atmosphere.
I appreciate the advice, but wouldn’t that apply if any aircon component is swapped out?
Pretty much although the refill process pulls a vacuum first and by doing this normally causes any moisture in the system to be expelled before the vacuum is held for the requisite time to ensure no leaks. If the drier has been in there a while makes sense to change it when the system is empty though as it is likely to be old and inefficient. They are around £30 (Hella for a BMR engined car such as mine).

Re: Aircon leak from high pressure pipework

Posted: Tue Jun 25, 2019 9:53 pm
by maclee
Yes, it would apply to anything that involves opening the refrigeration circuit, which, as you said, is most things. There are precious few exception, the pressure switch can usually be changed without evacuating the system, but that is generally-speaking, about it.

Replacement of any component in the refrigeration circuit, or indeed a loss of refrigerant due to a leak, will allow atmospheric air into the circuit, (in variable amounts according to the nature of the opening of the circuit).

This will bring with it moisture, which can do damage to the system, mainly to the compressor, although other components are also at risk.

For this reason, before the system is recharged it is subject to a vacuum for a period of time. The removal of the air is the primary purpose of this process, but the system is then left under vacuum for as long as reasonably possible, (usually a minimum of 45 mins), to cause the vaporisation of any remaining water droplets. It also serves to perform a negative-pressure leak test of the system, but the primary purpose is to vaporise any remaining moisture, - the moisture turning to water vapour, (boiling) under the low pressure conditions.

This vaporised moisture will remain even after the system is charged.

The dryer contains a desiccant which will quickly absorb, and then retain this remaining moisture as the refrigerant carries it around the circuit for the first few times.

Your dryer has been exposed to atmospheric conditions already, (when new and in storage they have bungs in the openings to keep air out), and will be more so when you replace that pipework. It is quiet likely that the desiccant in your current dryer is already close to saturation, and if that is the case it may not be able to arrest moisture that remains after the system is recharged, shortening the life of other components.

Reading my original post I did not make the thinking as clear as I could have. Apologies for that.

Re: Aircon leak from high pressure pipework

Posted: Tue Jun 25, 2019 10:22 pm
by jasimog
DMitch16 wrote:
Tue Jun 25, 2019 9:36 pm
If the drier has been in there a while makes sense to change it when the system is empty though as it is likely to be old and inefficient. They are around £30 (Hella for a BMR engined car such as mine).
Agree, but I'm thinking that with that amount of work just to access the dryer then I may as well replace the condenser too - it doesn't look too good and could well be the next component to fail. The dryer housing looks to be an integral part of the condenser, so would a new condenser come with a dryer core fitted?

Re: Aircon leak from high pressure pipework

Posted: Tue Jun 25, 2019 10:34 pm
by DMitch16
jasimog wrote:
Tue Jun 25, 2019 10:22 pm
DMitch16 wrote:
Tue Jun 25, 2019 9:36 pm
If the drier has been in there a while makes sense to change it when the system is empty though as it is likely to be old and inefficient. They are around £30 (Hella for a BMR engined car such as mine).
Agree, but I'm thinking that with that amount of work just to access the dryer then I may as well replace the condenser too - it doesn't look too good and could well be the next component to fail. The dryer housing looks to be an integral part of the condenser, so would a new condenser come with a dryer core fitted?
Depends where you get it from - some do, some don't. You'd need 2 new o-ring seals for the condenser pipes too. The Behr (Hella) condenser I bought came with the dryer and was £75 but they are cheaper for lesser known but good quality brands such as Dasis and Thermotec (£45 with dryer plus £8 odd postage - Auto Doc) but make sure you get the right size.

Re: Aircon leak from high pressure pipework

Posted: Tue Jun 25, 2019 10:53 pm
by DMitch16
maclee wrote:
Tue Jun 25, 2019 9:53 pm
Yes, it would apply to anything that involves opening the refrigeration circuit, which, as you said, is most things. There are precious few exception, the pressure switch can usually be changed without evacuating the system, but that is generally-speaking, about it.

Replacement of any component in the refrigeration circuit, or indeed a loss of refrigerant due to a leak, will allow atmospheric air into the circuit, (in variable amounts according to the nature of the opening of the circuit).

This will bring with it moisture, which can do damage to the system, mainly to the compressor, although other components are also at risk.

For this reason, before the system is recharged it is subject to a vacuum for a period of time. The removal of the air is the primary purpose of this process, but the system is then left under vacuum for as long as reasonably possible, (usually a minimum of 45 mins), to cause the vaporisation of any remaining water droplets. It also serves to perform a negative-pressure leak test of the system, but the primary purpose is to vaporise any remaining moisture, - the moisture turning to water vapour, (boiling) under the low pressure conditions.

This vaporised moisture will remain even after the system is charged.

The dryer contains a desiccant which will quickly absorb, and then retain this remaining moisture as the refrigerant carries it around the circuit for the first few times.

Your dryer has been exposed to atmospheric conditions already, (when new and in storage they have bungs in the openings to keep air out), and will be more so when you replace that pipework. It is quiet likely that the desiccant in your current dryer is already close to saturation, and if that is the case it may not be able to arrest moisture that remains after the system is recharged, shortening the life of other components.

Reading my original post I did not make the thinking as clear as I could have. Apologies for that.
That concise explanation is almost enough to make me hang up my Mastercool guages! You forgot to mention that half the circuit is gaseous and half of it liquid and the transition between the low pressure and high pressure sides? Perhaps Jasimog should change the expansion valve too and don't even get me started on the evaporator! :hyst

Seriously, great explanation for those that don't yet understand these things :ymapplause: :-bd

Re: Aircon leak from high pressure pipework

Posted: Wed Jun 26, 2019 12:46 am
by maclee
I greatly appreciate your kind words.

Thank you.

Re: Aircon leak from high pressure pipework

Posted: Fri Jul 26, 2019 5:42 pm
by jasimog
Now sorted. I replaced the high pressure (HP) and low pressure (LP) pipework last weekend. I also fitted a new condenser with dryer.

The original leak was on the HP line circled here (located under fuel filter):
aircon1.jpg
The coolant reservoir and fuel filter can be moved out of the way without disconnection. It would be possible to replace the LP pipework by itself, but to replace the HP line (which sits underneath the LP line) you need to remove both. You also need to remove the right hand engine mount. The bulkhead connections are hard to reach, but can be done from underneath with the front of the car supported on axle stands.

I bought the new HP line (non-OEM) from eBay and it was shipped from Poland (about £50 in total). It didn't come with the pressure sensor or temperature shielding fitted on the flexi hose section that runs up the bulkhead, so I swapped over the pressure sensor (screw fit) from the old pipe and cleanly cut off the heat shielding to transfer over too. The LP pipe was bought second hand from a car about 4 years newer than mine.

To replace the condenser I followed some steps found online rather the Haynes method. Haynes suggests removing the radiator and intercooler first, but the job can be done from the front (leaving the rad and intercooler connected up). After removing the outer bumper and its metal section underneath, the radiator can be supported on a jack with a block of wood to spread the load. Then the whole assembly is lifted up to release the intercooler from its mounts and allowing the plastic skirt to be pulled forward. There is enough space to undo the 4 condenser mounting screws and drop it out from the car.

I didn't connect up the new condenser until the pipework was all back together (to avoid exposing the dryer to atmosphere) so here's a pic of the condenser fitted but before connecting up:
aircon2.JPG
Finally the system was recommissioned and regassed by my friendly mobile aircon service who diagnosed the leak in the first place. I was nervous about the seals - 6 were disturbed in total (2 on bulkhead, 2 on condenser, pressure sensor and the LP connection to the compressor). I kept them all clean and used a small dab of mineral oil on each one before connecting up (aircon technician's advice). Anyway, all was good with no leaks. Very happy with the result given the current weather :D

Re: Aircon leak from high pressure pipework

Posted: Sat Jul 27, 2019 12:27 pm
by DMitch16
Is a great feeling when you recommission something like that. My AC is back up after a year of not functioning - just in time for the heatwave and forthcoming holiday.

Nice result and some good pics!

Re: Aircon leak from high pressure pipework

Posted: Wed Jul 31, 2019 5:43 pm
by jasimog
DMitch16 wrote:
Sat Jul 27, 2019 12:27 pm
Nice result and some good pics!
:esm

The car is 14 years old next week and is running well at nearly 200k, "non-essential" repairs like this are only cost effective when doing them yourself B-)

Re: Aircon leak from high pressure pipework

Posted: Wed Jul 31, 2019 10:00 pm
by DMitch16
jasimog wrote:
Wed Jul 31, 2019 5:43 pm
DMitch16 wrote:
Sat Jul 27, 2019 12:27 pm
Nice result and some good pics!
:esm

The car is 14 years old next week and is running well at nearly 200k, "non-essential" repairs like this are only cost effective when doing them yourself B-)
Same for my 12 year old 220k Sport. Time soon for an intake valve clean but I might just throw a metal non flap intake on her while I'm at it to replace the plastic swirl flap version.