Aircon just blowing warm air on hot days

[mbedford]

Hi all, looking for a bit of advice please.

On days over 25° aircon is working ok for about the first half hour, then it just gives up and despite trying to lower the temperature and using the 'cabin air re-circulation' button so its not pulling in outside hot air, the air con just blows out warm'ish air.

I put it down first to having a german car not designed for hot australian conditions with a big and hot V8 in the front and it just can't cope.

Ive had the air con re-gassed last summer, which i think did help it a bit.

A friend said the compressor could need replacing as its a 10 year old compressor now. He said his mechanic said to replace german air-con compressors with japanese ones as they are much better, sounds a bit strange to me.

Anyway the cars a 2007 B7 RS4 110k on the clock.

Any advice please?

[DirkOz]

Check aircon belt tension.
Check that the air con clutch is engaging - electrical test.
Check pressure switch and thermostat.
Use a thermometer in the outlet, and record the temperature of the air coming through the vents.
That's a good indicator too.

At licenced air con technician, ask them to check it out thoroughly.
Check gas level and gas leak test with their machine.
Compressors do wear out, but 110,000 km seems a bit early for compressor failure.
There is a small filter in the fluid return, normally located under the battery tray, that should be replaced, when servicing air con systems.
They can also put a cleaner through the system.
New air conditioner compressors can be sourced fairly cheaply from China, if the compressor has failed.
You'll need the OEM Part numbers, and do a bit of net-surfing.
I recently bought a compressor and a condenser from Kasen Air Conditioner Parts (China) Limited.
Other parts I bought from the US on run-out special, combined with some other engine parts, which were pretty cheap too.
Note: I haven't fitted them up yet, but I had a mobile guy come to de-gas, and check my system before I ordered the parts he recommended.
Filter, receiver/drier, compressor, condensor.
Strongly suggest get your system checked first, and then get the parts, and ask them to fit them.
Local repair guys won't offer warranty, unless you buy all parts from them though.
But you'll save enough that it shouldn't worry you.
Just wait 'till you get a quote!
I'm in Canberra, and can recommend 2 locals.
Where are you?
Perhaps others may recommend someone close to you who can assist you.

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[mbedford]

Thanks for all your advice mate

I am in Central Sydney in Darlinghurst, the car has been serviced for the past 2 years at BMS AutoHaus which I trust and do a good job I haven't asked him to look at the air con just yet.

[Pickles]

Check the gas,...could be too much?...or not enough.
Had the same issue in a new HSV GTO,...in hot weather the A/c simply stopped working, then at lower temps it was ok. Dealer checked the gas,....20% too much gas,...dropped some gas,...problem fixed.
What was happening was that in hot weather, the system over preasurised because it was over gassed, so the compressor cut out!!
Pickles.

[DirkOz]

Hope everything works out for you.
Once it's looked at by a trusted professional, take it from there.

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[(((sonic)))]

I had a similar problem on my A5, from memory it had a faulty 'flapper valve' - would only blow warm/hot air........


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[mbedford]

Can I just check with the other B7 (that's 2004–2008) RS4 owners if their aircon copes well on days over 25 degree's?

[27litres]

Nothing wrong with Bosch compressors, or Audi airconditioning. Both my Audi's have had far superior aircon to any of my Commondores that came before.

Not that there's anything wrong with Japanese compressors either, and if you can get a Nippon cheaper than a Bosch go for it.
I wouldn't trust a Chinese compressor - their quality control just isn't up there with the big boys... yet.

Find out what's wrong then take a look at FCPEuro for the parts you need.
Rockauto had the cheapest compressors last time I looked.

[DirkOz]

You can wait for advice from other owners, but best to call an Audi Service Centre, as an experienced service advisor would know if the problem is common or not.
Audi would most likely want you to book in for check.
Yours would definitely not be the first to exhibit this problem.
Audi have Service Advisory Bulletins, that others (not Audi) won't have access to.
Audi Centre will use only genuine parts, so costs can blow out for replacement parts that may be needed.
Basic maintenance :-
1. Properly adjusted drive belt
2. New pollen filter
3. Clean the radiator

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[Falco]

I have this issue on my B5 rs4. I have put it down to the Servo motor that controls the recirc flap having failed. Apparently a common problem as the motor is really too small for the task and burns out over time.
I haven't replaced it yet because its a dash out job which means 10 plus hours of work to replace a tiny servo. There was no noticeable different between fresh air and recirc air. I had 1 fault originally saying position fault on the air diverter, shop reset it and no faults since but no cold air on hot days.