Air Con Leak - Low Pressure Side

[willdudeuk]

Got an air con leak on low pressure side..... doesn’t hold vacuum.

any ideas? Going to replace seals first.

condenser was replaced last year with ECP EIS Part (222440611 (tel:222440611)) from memory.

[willdudeuk]

Replaced the following seals and performing another vacuum test.


4E0 260 749 A
3D0 260 749 C
8E0 260 749 C

The 8E0 I removed was damaged so hopefully that was the problem. A small piece was missing from the seal.

38174

[Crasher]

We have trouble with a Golf 5 GTI last week, in the end we found debris from the compressor in the expansion valve, you can store meat in there now it is so cold.

[willdudeuk]

It’s passed the vacuum test and been injected with r134a. It gets cold but not down to 8 degrees centigrade when we use a probe in the dash vents. It’s probably about 11/12 it goes down a bit up one acceleration but doesn’t reach 8.

weak pump?

where is the expansion valve on the Mk5 BAG engine?

If you have any pictures or diagrams that would be great.

thanks

[willdudeuk]

Air con is working.

but still got fault codes on ODIS.

the ECON light / button doesn’t come on when I press it. It’s constantly out the LED. But does appear to turn compressor ON and OFF as the air does go cold and then hot when pressed again.

A/C Compressor Regulator Valve N280
0008- Climate Control Module
898 10 A/C Compressor activation (open circuit / short circuit to B+ Intermittent)


Refrigerant Pressure
0008- Climate Control Module
229 2 Refrigerant Pressure (lower limit not reached - intermittent)

[Crasher]

If it has a Sanden compressor they are very problematic, we insist on Denso new, not recon. The expansion valve is the coupling on the bulkhead to the evaporator. Genuine they are insane money (hundreds) but Febi list them in the tens but have no stock! ECP have Hella for a good price.

[willdudeuk]

I’ll take a look but not sure is the labels are still on it.

Ive seen you can replace the N280 valve or that not worth doing?


Do I need to replace both compressor and expansion valve? With those codes above?

00898 and 00229


can find Mahle expansion valve on ECP 234440080

[Crasher]

You need to replace the compressor, to satisfy the warranty you MUST replace the receiver drier therefore complete condenser. The Mahle expansion valve is good.

[willdudeuk]

Is the complete evaporator the condenser? Or am I getting confused? I replaced the condenser with ECP 222440611

[Crasher]

The receiver drier is part of the condenser, we used that same unit as you last week but I think to fulfil the warranty you may have to do it again or risk it. The evaporator is in the heater box and evil work to change

[willdudeuk]

What will just replacing the expansion valve achieve?

will just replacing the compressor clear the above faults?

im not sure I can afford a new one at the moment - they aren’t cheap!!

[willdudeuk]

Well looks like I’ve got no ac now so guess I’ve lost the refrigerant somewhere overnight. Not blowing cold at all.

So will I need to replace Expansion valve and compressor?

Dont think I’m keen on replacing the evaporator. That job looks evil. That’s dash out / cross car beam / HVAC unit. Don’t think I’m keen on that at all.

is expansion valve easy enough to do? Can you do it from the top or is there better access from underneath?

[willdudeuk]

I replaced the valves in both the low pressure and high pressure pipes as it appeared that one of them was "bubbling" so this could of been a cause as to why i lost all the refrigerant overnight.

When we got it back on the machine it read 0 bar.......

Regassed it now....but wasn't achieving 8 degrees c, only about 14 this time....so must be a bad compressor.....


Replaced both valves with 8E0 820 855 genuine from dealership.....

But after regassing both appeared to be bubbling as well.....

I made sure to tighten them well with the valve tool....


Perhaps the threads have gone on the pipes?

[Crasher]

My mechanic Matt ran into this with his 1.4 TSI Golf 5 a few days ago, he recommissioned the AC after it had been dead for years and it worked, then it stopped and the compressor has failed, they suffer a very high failure rate. He is in denial and is trying to find any way of avoiding changing it.

[willdudeuk]

Well it’s lost all the gas again after replacing the valves.....

Which pump do I need?

Ive found a new genuine one with part number 1K0 820 859 T

are these exchange / recon units from factory? (Pump says T but box has TX).

[willdudeuk]

Going to replace the compressor with 1K0 820 859 T and hopefully see what happens.

Should I replace expansion valve at same time one it’s been vacuumed? It doesn’t have any pressure at the moment showing 0bar.....so it’s leaked out somewhere again.

The compressor looks like probably OEM part and looks a bit knackered to be honest.

Can’t see any leaks with UV torch though. Have checked as thoroughly as I could. The oil / lubricant we use has some uv dye in it but can’t see anything obvious.

I replaced the schrader valves for both the low pressure and high pressure lines but could still see it bubbling after we regassed it. Any reason why this would be happening? Could the threads or refrigerant pipes be knackered?

is replacing compressor first a better idea seeing as they are a common failure?

[Crasher]

There is no point doing the compressor until you find the leak, the most common cause is the pressure sender.

[willdudeuk]

I did replace the pressure sender / thrust sensor with the following part.....5K0 959 126

replaced the o ring seal too

cant seem to find a leak here unless the part is wrong? You can see in the picture that the old part looks different to the new one?

38299

[Crasher]

That is the correct updated sender, have you done a UV dye leak detection test?

[willdudeuk]

I am about to do it with some Wurth leak detection dye (Art. No. 892 764010).

Hopefully should be able to find the leak with this and a UV torch.

38302

[Crasher]

I love Wurth products, I have the catalogue beside my bed and read it cover to cover...:eek:

[willdudeuk]

Couldn’t find anything with the leak detection dye which was a bit of a pain! Might need a brighter UV light to help find the leak I think. Still only getting 10 degrees centigrade....think the compressor must not be running correctly or is worn out.....

any suggestions on what to do next?

i even got the glovebox out and removed pollen filter to check the evaporator.....couldn’t see any leaks when shining a torch up there and using an inspection mirror....

im at a bit a loss as to why the gas is leaking out (normally happens over a day or two, so has to be a fairly slowish leak, just can’t detect it).

[Crasher]

Those compressors are very unreliable, often made by Sanden and we fit brand new Denso units.

[willdudeuk]

Replaced the compressor (Denso 1K0 820 859 T) the other day and regassed - appears to be working great now! Holding pressure. The old compressor looked damp so there must of been a leak within the unit somewhere.

Getting around 9 degrees Celsius at the side air vent with a temperature probe.

Was hoping it would be a little cooler.

What do everyone else get out there? Is this value in the right ball park or should it be cooler?

[Crasher]

Give it time to run in which really you should do using VCDS.

[willdudeuk]

What can I do on VCDS to help me? Output tests?

[Crasher]

There is a run in setting in basic settings but it will do it on its own over time.

[willdudeuk]

Can see the high pressure schrader valve appears to bubble when the ac is in use.... so guessing there is a leak there but I

did replace the valve with a new genuine OEM part so can only guess that I’ve got a bad replacement valve or the whole ac

pipe needs to be replaced.


Any ideas why this is happening?

I made sure the valve is properly seated but still appears to bubble / leak.

Appreciate any help or advice?

thanks

[willdudeuk]

Been using the AC for a while now but it’s performance seems to have gone down. Doesn’t appear to be as cold. Must be a refrigerant leak? VCDS is showing 6bar as the refrigerant pressure. Could it be a bad compressor (even though it’s brand new Genuine OEM Denso part?). Or maybe something wrong with the blend flap? Need to check for leaks again and inject with dye and get a UV lamp out again. Hopefully it’s not the condenser or evaporator.

[Crasher]

It needs to be checked on a proper AC system test machine now. I have never had a new Denso fail but it is always possible.

[willdudeuk]

Ok no worries I’ll get it hooked up and see what the Low and High pressures are like. We had no issues vacuuming the system and it holding vacuum. It passed that test otherwise it won’t proceed to injecting gas into system. Perhaps there is an issue when it’s pressurised? Leak somewhere? But seeing as there is still pressure / refrigerant must be ok?

Can the expansion valve have an impact on the cooling performance?

Condenser was replaced as it was the original one and had taken a beating….so may not be that.

[Crasher]

I had the expansion valve on one cause me grief the end of last year, I hardly ever have to replace them. Genuine were daft money but by Febi incredibly cheap.

[willdudeuk]

If the are playing up what can happen? They fail internally? Anything I can look for?

[Crasher]

It was on a 2006 ish Golf 5 GTI and we suspected it was the compressor so we changed it plus the condenser as stipulated together with a new sender but the system would not work so we fitted a new valve which fixed it.

[willdudeuk]

Ok thank you (shall try replacing the expansion valve as everything else is new).

Are you referring to the pressure sensor which is screwed down in Z at the bottom next to condenser as the “sender”?

[Crasher]

Yes, sender, sensor, same thing.

[willdudeuk]

Well the AC has gone again….no more cold air from the vent….need to check but pretty sure lost pressure (again!).

When I remove the plastic cap on the high pressure side (thicker diameter pipe that goes from expansion valve to compressor 1K0 820 743) you can see it bubbling. So must be leaking from here. The schrader valve has been replaced with a brand new genuine VW part (8E0 820 855) so don’t understand why it’s leaking (unless it a bad valve or the pipe thread is worn).

Any advice on this please?

[VAG-Abound]

It's the same valve on the smaller pipe to condensor, so you could swap them over to see if the problem follows the valve or stays with the pipe's connection. If the latter then personally if it did get a breaker part 1K0820743CA that fits BAG, BKG, BLP and BLF engines. It's likely to have original valve fitted, and be leak free. New seals 4E0260749B and 8E0260749C, but you may have mentioned those higher up while trying other things.

[willdudeuk]

Thanks VAG-Abound I will give that a go. Seems strange that a new valve would be bad. I’ll try swapping them around and see what happens. Perhaps the pipe is damaged somewhere - should really inject with dye and get the UV lamp out but I’ve never had much success with that method. Think I’m not doing it correctly.

I’ll go and find some replacement pipes for the whole system (think there is 3 in total 1K0 820 743 CA, 1K0 820 721 AK, 1K0 820 741 BD) Can’t be much else left to replace other than the evaporator behind the dashboard / bulkhead.

[willdudeuk]

Just checked under the bonnet to see if both fans were running (when the AC is on) but they weren't.

Did a fault code scan and no codes......

Could the controller on the rad pack have gone?

Should I be looking for replacement fans? Would that stop the AC from working?

[Crasher]

The AC will shut down if the fans don't run and controller failure in the main fan is very common. Try operating the fans in output tests of the engine and HVAC

[willdudeuk]

Yep tried the sequential tests in output tests on the engine module but had no luck. They didn’t run so must be dead. That means a very expensive trip to the dealership then. What are the latest part numbers for the both the fans? Or should I just replace the bigger one first that has the controller on it?

But I thought I would at least get a code for the fan failure but I don’t have anything from VCDS.

[Crasher]

What is the VIN?

[willdudeuk]

Wvwzzz1kz4w096975

My guess is 1K0 959 455 EA and 1K0 959 455 ES.

[Crasher]

Yes, but on an older car like that we would fit EIS Radiator Fan | Euro Car Parts (https://www.eurocarparts.com/search/213440290)

[willdudeuk]

Ok thanks Steve. I ve managed to find a genuine one for a good price. Should I start with replacing the big fan first?

Is the fan completely dead? I’ve not noticed it coming on in the hot weather? However the coolant gauge has always remained at 90 and never gone into the red so not aware that it’s overheating.

The compressor is still coming on when looking at the measuring blocks in VCDS. If the fans don’t come on would that prevent the cabin vents blowing cool air?

[Crasher]

I did that once, the first time and found it was the small fan which had failed and burnt out the controller so I had two dead main fans, the old one and a brand new one... you live and learn. The compressor is being asked to compress but the faulty N280 valve is having none of it.

[willdudeuk]

Well strangely enough I did the output tests and both fans run. Does the fan for AC require the system to be at a certain pressure to operate? Or put another way what tells the fans to turn on / spin?

[Crasher]

I thought you tried that before and it didn't work?

[willdudeuk]

Yer I thought that too. But I pulled the plug and fuse for it in the hope it may reset it. Then tried again a they fired up. But they still aren’t coming when the AC is on so I’m guessing it’s related to the fact the system isn’t working currently. But trying to now narrow it down to whether it’s the fans or a leak somewhere.

As you have said in this forum no codes, no cold air means replace compressor (but it’s a brand new genuine denso unit 1K0 820 859 T).

[willdudeuk]

Had a look at the condenser through the front bumper….looks like it’s taken a few hits from stones / debris. I can clearly see the horizontals have been dinged in 2 areas (enough possibly to cause a leak) but cannot see any signs of oil / refrigerant. Would of thought if it was leaking from there I would see signs of this. Suspecting a hole in the condenser due to damage. However I thought this may have been picked up when performing the vac test prior to injecting the refrigerant. It holds vacuum without an issue.

38627386283862938630

[Crasher]

I have had a couple go but as Denso now stipulate you must fit a new one, this gets dealt with during the inevitable compressor change. You should see the way MQB ones rot and fall to bits.

[willdudeuk]

Not heard of MQB. Who are they? A manufacturer / supplier?

Do you think the damaged captured in the above images enough to cause a leak in the AC system?

[Crasher]

MQB is Modularer QuerBaukasten (Modular Transverse Matrix) which is the Golf 7 etc platform, Golf 5 is PQ35 (Passagier Quer or Passenger Transverse design 35), funnily enough about ten minutes after I typed that a Golf 7 pulled in with the condenser hanging in pieces. The condenser is not a common PQ35 platform issue, usually it is the pipe on the right inner wing.

[willdudeuk]

Ok thanks Crasher. So which pipe would that be? There are 2 AC lines running down that side. Do they wear through or fail in a particular place?

[Crasher]

Either of them can corrode through the ally where they touch anything, I forgot though, the pressure switch is extremely prone to leaking.

[willdudeuk]

I’ll have to get the system vacuumed and remove the pipes to confirm the condition of them.

The pressure switch got replaced with genuine OEM part so hopefully it isn’t leaking. The oring was also replaced with new OEM part.