Audi S4 2017 Aircon not working

Timothy!

Registered User
Hi all, new to the forum but I'm after some advice.

I have and S4 2017 and I am having issues with the air con. The option to switch the AC on is currently greyed out. The vents will blow out air on low but the option to turn on AC is not available. Does this mean I need to replace the gas or is this a technical fault. Thanks in advance.
 

cuke2u

Registered User
Could be either, is there any warranty left with the car? Even though you may not be able to have it looked at by a dealership under the current circumstances I would still log it with them as any fault reported under warranty should still be honoured when they eventually reopen..
 

Spearo

Registered User
Audi Cardiff told me in no uncertain terms that in my 3rd year of ownership that air con components and function were not covered by warranty! I questioned this but no dice in Cardiff - depends who your dealer is I suspect!
 

Spearo

Registered User
Meh- well, I went in with aircon that was hissing, I documented it here.
No cold air blowing and a prolonged hissing from vents.
Audi told me that air con components were subject to wear and tear and therefore not covered.
I ended up paying for fault finding (they couldn’t find any fault) and then for aircon service- basically a re- gas which fixed the problem ! ( this is while the car was 2.5 years old ) Audi said it just needed gas and there wasn’t a fault ! 9 months later and Its not working again and I’m out of warranty.... and Before lockdown they didn’t want to hear and now Audi is closed...... useless !
 

BigAardvaark

Registered User
Seems to be becoming a common fault this. You are all being fobbed off. If an air con system needs a regas it is leaking. I've had the same symptoms as you covered under warranty twice now, the 2nd time was in the 3rd year (regas with blue tracer dye) and has (fingers crossed) stayed working for 12 months, more than it did after the first fix - pressure sensor. No diag fees, nothing. A car of this age shouldn't have "worn out" the air conditioning.
 

cuke2u

Registered User
Agreed, unfortunately it seems Spearo has got a 'wayward' dealership....
 

rum4mo

Registered User
I seem to remember that at least VW recommend that you get the AC serviced at the 2 year point, a smart move by VW as if you did that and paid for it, VW Group warranty claims for lost gas would drop quite a bit, though probably still more than a few pressure sensors causing leaking.

They normally use the reason for needing a service as two fold, bacterial build up removal and remove, weigh and recharge fridge system as all these mobile AC systems have many "plastic" seals and flexible pipes which are slightly porous to all fridge gases so gas loss in a still intact system will always happen with time.
 

BigAardvaark

Registered User
I've had many cars but I've never had one needing as much attention to the A/C than this one and it seems to be getting quite the common subject in here. At this rate, it's going to be tough to find a 5 year old example of a B9 with gas in the system....
 

rum4mo

Registered User
There is seem to have been a trend with VW Group car with the latest air con gas needing more "topping up" than you might expect, now okay this latest gas comes with a lower ozone depleting number, but surely that is no excuse to have moved across to this gas before making sure all the system "plastics" are compatible with it, just very sloppy until there is some other reason for this. My wife's August 2015 VW Polo seems to lost most of its gas, but that is the older fridge gas, ie R134A - and I'm not too happy about that even if it turns out to be an evaporator failure - in which case I'll be extremely annoyed as replacing that will not be a pleasant job! My 2011 B8 S4 has only had one top up by me, so far, our previous 2000 VW Passat 4Motion lasted 13 years with its AC working okay from new, my wife's September 2002 VW Polo 1.4 also never had or needed any top ups over its 13 years life with us.

Edit:- older daughter's late 2019 SEAT Ibiza did need top'd up at about 8 year old, but that was caused by the pressure sensor leaking - too common a problem across the VW Group marques, and maybe still is.
 

cuke2u

Registered User
I've had many cars but I've never had one needing as much attention to the A/C than this one and it seems to be getting quite the common subject in here. At this rate, it's going to be tough to find a 5 year old example of a B9 with gas in the system....
Really, that's strange as I have had mine serviced as suggested and have had no issues and the climate system within the A4 is unlikely to be different from any other. I guess you've just been unlucky.
My A3 before was also faultless...
 

BigAardvaark

Registered User
Your A4 and A3 are exactly as my previous VAG cars have been, faultless, and I've had 9 of them now. Never had the A/C serviced on any of them. Most were over 5 years old when I moved on, some 100,000+ miles.

The 1st fault I had fixed at 20 months old was also classed as an A/C service but 9 months later same thing. No abuse, no switching off A/C over winter, etc, etc. Been on many a car forum too and the frequency we're seeing this issue here on the B9 section is beginning to look like common fault territory.
 

rum4mo

Registered User
@BigAardvaark, seeing as you have mentioned it in the passing, all these cars now have a variable displacement AC compressors fitted to them, so they run continuously if the AC is left on or deliberately switched off, so no excuses for handing the responsibility back to the way the customer has been using their car's AC when gas charge has been lost more than normal.
 

cuke2u

Registered User
Your A4 and A3 are exactly as my previous VAG cars have been, faultless, and I've had 9 of them now. Never had the A/C serviced on any of them. Most were over 5 years old when I moved on, some 100,000+ miles.

The 1st fault I had fixed at 20 months old was also classed as an A/C service but 9 months later same thing. No abuse, no switching off A/C over winter, etc, etc. Been on many a car forum too and the frequency we're seeing this issue here on the B9 section is beginning to look like common fault territory.
How many has there been though in here, 5 or 20? Plus we don't know if the systems have been serviced according to the correct regime and a tiny tiny number compared to the number of cars sold. A concern, perhaps, but let's not start jumping to conclusions running around shouting there everywhere until proper evidence is gathered...
 

BigAardvaark

Registered User
"beginning to look like" is hardly conclusion reached. Time will tell.
 

Spearo

Registered User
Mine was “serviced” in accordance with the schedule and then I had a problem with it - which was mysteriously remedied by a regas ( apparently Audi's investigation didn’t show any faults or leaks). Now I’ve had loads of cars, and some have required new gas to stay cool but only after 5 or 6 years.
So...... I maintain that there was a fault during warrantee that they probably couldn’t find or didn’t bother looking for ! My car was out of warranty in Jan and then in Feb, 9 months after my last regas, I have the same problem! Audi suggested that I pay for diagnostic inspection and regas ;-) .....Then came lockdown and
My appointment was cancelled!!!!!
So what do I do now - I don’t trust Audi to find the fault or even bother looking if they think that is a super slow leak that’s fixable, albeit temporarily, with a regas !
I think the plan is to go to an independent air con specialist, pay for a diagnostic service get them to hopefully find the fault and then go back to Audi and hopefully get them to fix it as goodwill - given that this is a reoccurrence of a problem that first occurred whilst under warranty!
Alternatively, I suppose I could get the likely failed components - fix them myself and just to to an independent for a regas????
I’m suspicious though that Audi know there is a problem and they’re fobbing off customers!!!!
 

BigAardvaark

Registered User

rum4mo

Registered User
@Spearo, you plan to get a proper AC specialist to find out what is wrong and then giving it back to Audi so that they will fix it does not seem to work with any VW Group dealership, and maybe some others, they will want to hit you or Audi with all the diagnostic costs then repair it if found faulty - though I'd think that they would be smart enough to take on board the diagnostics of a proper AC specialist and also see that you were not going to "fold" and pay up later.

If I were you, and it was an under bonnet part of the system that was faulty, I'd be taking the easy way out and let your proper AC specialist source the parts and fix it. Typically a proper AC specialist will end up buying genuine parts as there will not be any direct fit alternatives.
 

rum4mo

Registered User
Did a quick search and found the following members with the same if not similar issues;

@BigAardvaark @Smickers @Spearo @Timothy! @Corbula @WesT-gefül @BeagleKCH @Tedic15

There was a telling line in one of these threads, someone in the know had said to a potential buyer "Check the A/C, there's a pressure sensor that fails all the time on these".

The pressure sensor seems to have been an issue for VW Group for many many years for some strange reason, I've only needed to replace the one on my daughter's previous car a late 2009 Ibiza, you can tell when these sensors are leaking as there will be a "tell tale" oily dirty patch on the sensor, though I considered that it was due to a poor quality of materials or material finish which caused corrosion to set in and creep under the O-ring sealing area and then its game over for that sensor.
 

BigAardvaark

Registered User

Spearo

Registered User
@rum4mo - yeah you may have a point ...... Arguing with Audi is extra hassle that I don’t really need , but you know what it’s like - it’s the principle more than anything!
Does anybody know where this pressure sensor is in an S4 - I’d like to take a look myself before it goes anywhere !
 

rum4mo

Registered User
@rum4mo - yeah you may have a point ...... Arguing with Audi is extra hassle that I don’t really need , but you know what it’s like - it’s the principle more than anything!
Does anybody know where this pressure sensor is in an S4 - I’d like to take a look myself before it goes anywhere !

The fridge gas pressure sensor used to reside under the plastic cover that closes up the area above the radiator on the B8, I can't say for the B9 though basic logic would mean that Audi have left it in that area.
 

Steve A.

Registered User
Hi Guys.
As a recently retired Refrigeration Engineer. May I point out one basic fact about Vehicle AC. There will be occasions when a joint or sensor leak. But the most common fact is Leaking shaft seals on the AC compressor drive shaft.
The final drive which rotates the compressor is usually connected to the Belt driven pulley shaft by Magnetic coupling.
So Magnet energised = AC on Compressor rotates.
Magnet off = AC off Compressor stopped.
On the Compressor drive shaft there is a Viscus Shaft seal (Wet Seal ) which is maintained by the rotating shaft and seal faces (highly polished optical grade surfaces) being kept wet.
Think of it like the glass of water and card across the glass trick.
If the seal surface is smooth enough and kept wet it creates a strong enough seal to allow the demonstrator to invert the glass!
The AC not being used for any length of time (Say several months over winter) results in said shaft seal drying out and leaking.
Remedy. Run your AC for a couple of minutes once a week just to maintain the viscus seal which prevents the refrigerant from leaking out past the dry seal and to atmosphere.
Most car systems have a tiny amount of refigerant within them maybe 5/600 grammes. which will take quite a while to leak out.
But eventually your system pressure will drop enough to exibit a pressure sensor issue (Low pressure for example)
Sound Familiar?
I am not saying this is always the case but just run your AC briefly but regularly and you take the most common Fault out of the equation!

In fairness some modern cars use the AC on start up to demist the windscreen as the condenser side of the produces warm dry air Very quickly.
These type of systems are far more reliable.
However they still rely on warm air being required.
So next time no fault has been identified ( most Car mechanics are not trained on Car AC. ) The Service Plant they use does evrything for them.
And why not!
Less hassle for them.
Just think when did i last use the AC.
Use it or loose it!
Steve.
 

rum4mo

Registered User
@Steve.A., modern car HVAC compressors do not have clutches, they are directly driven and have variable displacement via a squish plate, so run at a minimum duty, ie pumping capacity when "not used/required" and so oil will be moving round the system at all times. I'd think that as well as any/all plastics being slightly porous to the fridge gas, the main possible damaged areas leading to leaks will be the condenser, followed unfortunately by the evaporator - that one is due to shoddy/cheap manufacture and has began to be an issue across the VW Group fleet, which can get a bit expensive for the owner.

Most large fridge system people would not touch car HVAC systems with a barge pole, leaving it as "each to their own thanks".

Edit:- I do agree with "let a proper car HVAC person look at it" though.
 

Steve A.

Registered User
Fair enough Rum4mo.
That's a newer development I was not aware of!
I only do the occasional evac (Reclaim), pressure test, deep vacuum and recharge for close family and friends.
Because as you say the liability nowadays is horrendous.
I did get caught out when the systems changed from R12 to R134a. Because as you elude to the molicules in the R134a are much smaller than the original R12.
Resulting in gas tight flexable hoses becoming porous. But that was probably 20 yrs ago now?
Your earlier comments if ratified?
Could help someones Future claim. Where an Inherrant Fault is Proven.
Time will tell!
Thanks for your Help.
Steve.
 

Spearo

Registered User
Let’s face it - I agree , a regas is often necessary but all it really does is help indicate where or what the problem is ! If there is low gas or no gas In The system then clearly you have a leak somewhere and that’s the issue that needs addressing and fixing before you have a proper regas !
Mine was dye traced to a faulty condenser- with a UV light I could see orange dye on the passenger lower front side of the condenser.....
I ended up taking the car to Audi, demanded a fix , shared with them the knowledge that I had gleaned from this forum about there being an updated /modified condenser produced from Audi and pointed out that that change had clearly been done because there was an issue!
eventually after some stamping of feet on my part the car was fixed - new condenser and regas at no cost to me thankfully!
So yes - a regas is helpful but only to help diagnose the cause
 
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