Aircon leak from high pressure pipework

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jasimog
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Aircon leak from high pressure pipework

Post by jasimog » Tue Jun 25, 2019 12:17 pm

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).
MY06 B6 Saloon SE, BKP. Self fitted: KMB balance shaft, recon turbo, clutch & DMF, Eibach Pro springs, retrofit Autohold.

maclee
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Re: Aircon leak from high pressure pipework

Post by maclee » Tue Jun 25, 2019 3:58 pm

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.


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Last edited by maclee on Tue Jun 25, 2019 10:01 pm, edited 1 time in total.

jasimog
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Re: Aircon leak from high pressure pipework

Post by jasimog » 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?
MY06 B6 Saloon SE, BKP. Self fitted: KMB balance shaft, recon turbo, clutch & DMF, Eibach Pro springs, retrofit Autohold.

DMitch16
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Re: Aircon leak from high pressure pipework

Post by DMitch16 » Tue Jun 25, 2019 9:36 pm

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).
Mad Mitch
B6 2007 2.0 Tdi 170 Sport DSG, BMR Engine, Phone Kit, Alarm chirps, Fogs as DRLs, Rain Auto Closure + VCDS MicroCAN, Double Oil Pump Drive Failure! Still Going 200K Club

maclee
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Re: Aircon leak from high pressure pipework

Post by maclee » 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.

jasimog
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Re: Aircon leak from high pressure pipework

Post by jasimog » 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?
MY06 B6 Saloon SE, BKP. Self fitted: KMB balance shaft, recon turbo, clutch & DMF, Eibach Pro springs, retrofit Autohold.

DMitch16
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Re: Aircon leak from high pressure pipework

Post by DMitch16 » Tue Jun 25, 2019 10:34 pm

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.
Mad Mitch
B6 2007 2.0 Tdi 170 Sport DSG, BMR Engine, Phone Kit, Alarm chirps, Fogs as DRLs, Rain Auto Closure + VCDS MicroCAN, Double Oil Pump Drive Failure! Still Going 200K Club

DMitch16
B7
Posts: 1050
Joined: Sun Jul 08, 2012 11:03 am
Passat model: B6 Sport 170 DSG
Location: Rustington, West Sussex

Re: Aircon leak from high pressure pipework

Post by DMitch16 » Tue Jun 25, 2019 10:53 pm

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
Mad Mitch
B6 2007 2.0 Tdi 170 Sport DSG, BMR Engine, Phone Kit, Alarm chirps, Fogs as DRLs, Rain Auto Closure + VCDS MicroCAN, Double Oil Pump Drive Failure! Still Going 200K Club

maclee
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Re: Aircon leak from high pressure pipework

Post by maclee » Wed Jun 26, 2019 12:46 am

I greatly appreciate your kind words.

Thank you.

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