I have a 2007 A8L and for some reason today the AC decides to stop working, it blew cold as ice for about 3 mins earlier then I decided I didn't need it and turned it off. This afternoon I turned it back on and it's been hot air ever since, any suggestions / comments?

 

Post up a complete Auto-Scan and we can see if there are any issues.

Could just be a low charge on the system.
We see these every fall and spring with heat and AC issues.

 

I can understand why one would think low charge as did I, but the car only has 60K miles on it. If the system is low at this point then there must be another problem. I checked ALL of the fuses, and they're good

 

Ahh... wasn't sure as the vehicle is 8 model years old
I'd still check it simply due to age.


That's why I suggested scanning it.
Otherwise you will just be throwing parts/$$$ at it without any real diagnosis.

 

00819 - High Pressure Sensor (G65)
002 - Lower Limit Exceeded - Intermittent
Freeze Frame:
Fault Status: 00100010
Fault Priority: 3
Fault Frequency: 4
Reset counter: 225
Mileage: 190496 km
Time Indication: 0
Date: 2014.06.12
Time: 20:07:42

getting this error and now can't switch ECONOMY MODE OFF
only hot air blows seems like compressor not kicking in

any help how and where to replace this sensor

thank you

 

Classic symptom of either low refrigerant or bad sensor.
00819 - Ross-Tech Wiki
Check all the wiring and MVBs before replacing though.

MVB info Audi Portal: Sensors Diagnostic . Audi A8 4E (2002 -). G65

I think it is #4 in this diagram, but not certain what year your Audi is. 2005 Audi A8 Quattro Parts - Audi Wholesale OEM Parts | Audi Genuine Accessories | Audi Branded Collection | Audi USA Parts Online Catalog estore

 

Hi
Thanks for details info
really helpful
so just check --- low refrigerant ----
tried some air instead of refrigerant , i can hear leak somewhere near to the compressor
i will need to lift the car up to trace it down.

thanks again for your help.

 

Had the timing belt replaced at 90K miles and the a/c didn't fire up. The outside temp sensor was disconnected as part of removing the grill for the belt replacement. Disconnecting the battery and letting the car sit quietly for 20 minutes let the computer reset. It took three attempts to work, but it did. The a/c has blowen ice cold ever since. At the 150K miles belt replacement, my mechanic didn't disconnect the sensor ( he worked around it) and the a/c works fine. I think I could make ice cream if I wanted to. Jetsam

 

Audi and VW systems are the worst. I have an A4 and I've had a Passat and Jetta. They do not cool like other cars do. I live in S. Florida and have two Acura's that blow ice cold A/C. The A4 and VW's do not.

 

Bias and personal preference based on alternate implementations, does not imply one is better.


Yep, an Acura will freeze you out and then you have to adjust it.

The A8, which this sub-forum is dedicated to, uses a slightly different system from the other VAG models mentioned.
This system has been refined over the years since the models originally discussed, many of which are now over 10 model years old.