Aircon Gurus needed

Broken Byzan

Broken Byzan

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Double post as this gets more traffic than the Aircon section

Ok, i had a faulty aricon compressor (Siezed), so had to drain the system and change the compressor. I did it straight away to avoid damge to the dryer. I also put a blast of one of those top up cans in to ensure it had some lube in the pipes to prevent any damage.

I took it to get it refiled, they drained and refilled to the prescribed amount, no leaks, rad fan working, clutch kicking in and out with the econ switch, but no aircon.

There are no codes on the Hvac unit and it is coded correctly. One of the alloy pipes by the firewall is slightly warmer that the other but thats it. It all seems to say its working, but it obviously isnt.

Anyone offer any help?
 
I dont know the mechanics of the system tbh, but when my aircon stopped on my 8L S3 which shared soemthings with the B5 IIRC there was a valve/sensor behind the firewall right at the top hidden that went faulty & anytime I had aircon turned on it wouldnt blow clean air as such but also didnt stay on econ mode which is a normal sign of faulty system, so was strange, they changed the part which was inline one of the pipes & it corrected this & straight away I had cold air on aircon mode
 
Faulty fixed orifice tube, (at firewall) or broken / dislodged temperature probe (in evaporator).
 
So anyone more likley than the other? Or do you want to just sell me both from that car i had the pump from,lol
 
How much gas did they charge the system with?

The correct charge amount is shown on a sticker in the engine bay
 
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Blocked/partialy blocked oriface tube (like Siena said)- it is located in the aircon tubing under the battery.It looks like a thin hair curler with a thin diameter tube running throught it. You will need to get the aircon discharged to get at it though.
It could be debris from the compressor failure.
You will need to flush out your system to ensure there are no metal bits floating around the pipes.
Was the firm who did the refill a good one- ie did they pull a vacumn on the system first to remove moisture?
If this hasnt been done it could be that the oriface tube is freezing itself shut.
Steer clear of those top up cans - they also introduce moisture.
Was the compressor a new one, or a known working second hand one?
The hot pipe would indicate that the compressor is working to some extent as the heat comes from compressing the refrigerent.
 
It was quick fit that did it no worky no charge job. I honestly assumed they vacuumed it all out as a matter of course.

So can i get it discharged and clear the blockage myself? Or is it time to change the pipe and be done with it. The compressor was a known good one from Siena. In fact i would bet my old one was ok just seized due to the blockage/pressure
 
Ok trawled Etka and have found this "Choke" 4B0 820 177. Is this AKA the Orofice tube?
As it's not too expensive to order new
 
Yep thats the orifice tube.
Did you get a print out from quickfit with how much refrigerent was added? and does it match the Audi sticker amount on the underside of the bonnet.
Too much refrigerent can also stop the aircon working.
Its illegal to knowing discharge refrigerent into the atmosphere- plus the cost of the stuff it might be worth getting someone to recover it so it can be put back in. The system will have to be empty to swap the tube and flush the pipes out- the flush is done with chemicals thought - not a hose pipe.
The reason a vacumn is pulled is water boils at a lower temperature in a vacumn so by pulling a vacumn on the aircon and holding it the moisture boils away- its also useful for sucking the new refrigerent in.
Moisture is the enemy of aircon - it turns the oil for the compresser into a sludge and it freezes up the oriface tube.
It might be time to take it to a aircon specialist rather than a garage that has a automatic machine for regassing.
Audi A4 compressors do have a known problem of the inerds (swash plate)going in them which can lead to debris in pipes.
Fixing aircon can get a bit pricey as there is always a regas cost- I would go over all the external stuff again before cracking the pipes again.
 
Is one of the pipes going into the firewall/bulkhead on the passenger side as cold as say inside a freezer?This would indicate some form of aircon occuring.
Perhaps one of the air distribution flaps is not working?
I would have thought a fully blocked oriface tube would trigger the high pressure warning whickh would show up on vagcom
 
At the mo i have nothing but time as i do not work, so as such cannot afford to just give it to a "specialist" to look at. The comp is a known good one so i will get the thing sucked out. Change the pipe myself and go from there i spose, at least QF offer not to charge if the aircon doesnt work afterwards, hence using them.

As for external stuff, if you mean fans, magnetic clutch etc, it all does what it should, wothout throwing codes etc.

I do appreciate your replies tho, you sir are a knowledgable person, what would you recomend i check externally?
 
jameshughes1974 said:
Is one of the pipes going into the firewall/bulkhead on the passenger side as cold as say inside a freezer?This would indicate some form of aircon occuring.
Perhaps one of the air distribution flaps is not working?
I would have thought a fully blocked oriface tube would trigger the high pressure warning whickh would show up on vagcom
Click to expand...

One is deffo cooler than the other. One gets warm a,d one is cooler than ambient temp. The flaps are all showing as working and in fact i can stick it on hot no problems at all. VAG shows no fault, nor does the aircon HVAC unit
 
There isnt much to check externally and it sounds if you have done it already I say check to avoid sending people down expensive routes that dont fix it!- fans running etc - compressor clicking on with the corresponding drop then recovery in engine revs as the extra load of trying to squeeze refrigerent through a little hole kicks in.
As you say vagcom will show any codes to do with sensors not working.
Yours is likely blocked but not quite blocked enough to throw a code.
On a working system one of the pipes that comes into the bulkhead will be cold enough to have beads of condensation on it.
It might be worth you or Siena (if he has you old compressor) taking the old compressor apart first(al least that wont cost you for a regas) to look for the mechanical damage- ie bits of metal floating around.That way you might get a better idea of what kind of stuff might be floating about.
Think of the oriface tube as a bigger diameter nozzle on a spray can - say wd40 for example - it wouldnt take much to clog one up.
You could also check the aircon rad -(aka the condensor) it is there to cool the compressed refrigerent- for a sudden temp change- although this would be a bit vague.
So from the outlet of the compressor- the refrigerent goes through the dryer and condensor before it gets to the oriface tube.
After the oriface tube it goes to the evapourator which lives behind the blower motor, you would have to be seriously unlucky for that to be blocked thought.
Take the old compressor apart and see what size lumps are floating around in it.

There is another option - Have quick fit messed up the regas and lost some of the refrigerent to the atmosphere? - this would not show up on their machine and unless its enough to trigger the low pressure switch on the aircon it wont show on vagcom
 
Thanks, i did look into the old comp to see if there were visable signs of anything when it was removed. I will whack the back off in a bit to see, you have spiked my interest now. It used to give me condensation on the pipes but when the compressor started to get noisey it stopped working, and would stall the engine on tickover due to high load.

So i may need to seek someone that can do this without shafting me. Anyone recomended in the southwales area that works for pocket money for VAG owners?
 
Thanks, i did look into the old comp to see if there were visable signs of anything when it was removed. I will whack the back off in a bit to see, you have spiked my interest now. It used to give me condensation on the pipes but when the compressor started to get noisey it stopped working, and would stall the engine on tickover due to high load.

So i may need to seek someone that can do this without shafting me. Anyone recomended in the southwales area that works for pocket money for VAG owners?
 
I dont know of any specialist in your area but you might get more info from a domestic aircon engineer who does cars for a bit on the side - they will have an understanding of what the system is meant to be doing rather than just refilling it, most garages fall into the refill catogory regardless of the specialist aircon badge they all like touting.

I would also get a pressure reading on the high and low service valves with the aircon off(Quick fit may be able to do this for you)and when it is running

If you could post the numbers it might help point you in the right direction.
The reading with aircon off (and it needs to have been off for say half an hour) should help find out how much refrigerent is in the system.
With it running we would be looking for unusally low or high numbers which would indicate a blockage and maybe which side of the compresser it is on.
Also make a note of the outside temperature as aircon pressures are temperature dependant.
The above can be done without losing your refrigerent
 
you need a puller to get the clutch off - but as your old compressor is stuffed already there is no harm in distroying it for "diagnostic purposes"
 
Ok, so i took apart my old compressor and found a disintergrated wave washer hiding down below where the pistons are ( crankcase?) so that would have caused the periodic siezing, but is this area open to the r134a? to allow particles to make it to the rest of the system?
100_3391.jpg


So assuming this was the failiure and assuming the current pump is still ok, will i now need a drier and choke? or will a decent flush ( not with hosepipe,lol) suffice?
 
Well that looks like 1.5 washers so where is the other halve!?
I think you have a blockage in between the compressor outlet and the orifice tube.
If you wanted to be legit you could take it back to quick fit and ask them to remove the refrigerent(for free) then you could take it home to work on- judging by the size of them bits the blockage may actualy be in the condenser - chances are bits that big are going to rattle if you shake them.
If you have the time then take the pipe work and condenser out.
You could try a solvent cleaner such as brake and clutch cleaner in them as this will evapourate after a while a lot quicker than water.
Dried compressed air might be useful as well.
I dont know if you can flush filter driers - some how i doubt it - but agood shake might bring something out.
Once you have it back together try again.
You must get all the bits out though as you dont want them shooting through the new compressor.
You might not need a new orifice tube - if the gauze is intact and it isnt blocked it will be ok.
Filter dryer - They are there to take moisture out - i havent figured out yet if this the aircon equivelent of redex - ie changing it does nothing - if a system has a vacumn drawn and is regased properly why do we have to change this - i think it falls into the "it does no harm to change it" theory - however yours might have a big lump of washer stuck in it and they are cheaper on ebay then they used to be
 
Th 0.5 washer is the small bits i found. Adds up to a whole half.....?? At least as best as i can assemble anyway

Ok will get it recovered and start by dropping the pump connectors and blowing from the orifice back with a compressor i think, should give indication of where blockage lies i assume, **** could really do without this, at least its a non critical system i suppose
 
Yep - you are still mobile so you can live without the aircon.
I would still get the pressure diag done first though - the info might be useful.
See what some of the others on the forum think before cracking on with the job a second opinion might throw a different light.
Keep us updated - its intresting to see how these things are resolved and is good info for other readers/audi owners.
I got my aircon experience with a pug 306(salt corroded aluminium pipes) and then my audi a4 - mine cost me a new compressor although it didnt chuck bits of metal about like yours but probably wasnt far away from it.
And my last thought for the day is they never "just need a regas" aircon is a sealed system - if yours is empty its because there is a expensive hole in it!!
 
Mine was empty from when the noisey pump was removed and replaced. I will update, as it keeps the forum useful for anyone else in a siliar situation
 
What was the outcome of this Byzan ??? did you resolve it ??? sunny weather is here and my Dads A4 is playing up.... going to get it gassed first thing tomorrow.... to me the clutch dosn't seem to be kicking in... if it was low on gas or preassure would this be dissabled so as to not cause damage ???...... the other thing is... when everything is turned off and keys are out of the ignition.... if you listen carefully you can hear the flap motors twitching back ond forth.... it did have some work done in this area when he bought it as it would only blow cold air... that side of things seems ok now other than the twiching motors... but we wanna get this aircon sorted..
 
Mine had to be completly evacuated and re gassed and oiled once i had fitted a known working pump. Still working now AFAIK

Kwik fit do a good deal on the no fill/no working aircon, no charge thing.

Thats the total of thier knowledge so do not expect a diagnosis, but you will either drive away with working aircon £40 lighter, or drive away with a non working aircon system at no charge, i don't see how you can lose.
 
Has anyone any idea what their current regas prices are? I'm sure mine could be colder, now that I've actually fixed it - but it's had a fair few disposable cans thrown in over the years and I'd like everything sucked out and the exact amount of gas put in, so I'll drop by tomorrow. Don't mind paying £40, but I've read £25, £35, £40, £60!
I will be standing beside matey watching his machine to make sure he puts in exactly 725g of gas!
 
I have a aircon machine and I'm qualified!

Most places are around £45 don't go for a quick 20min vac, I left my own S3 for 5 hours on vac following a compressor change.
 
Fella says it'll take an hour - I work in (building) air-con and have seen what happens when you pull too hard a vacuum - condensor/pipe collapse.
I'm just going to get him to suck it out, then regas it and add the oil - if it makes no noticable improvement then he won't get paid, simple as that.
 
No need to go below -30psi

Only add the same amount of oil that gets removed and make sure it's the correct pag grade oil for your compressor.
 
Quick fit did my das a couple of weeks back about £45 i think but garaunteed money back if they don't drop your temp by 10 degrees
 
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