Hi All, I have a 2001 A6 2.8 Quattro wagon that just recently decided to be intermittent with the air conditioning.
When it's running properly it puts out nice cold air so I don't believe there is a problem with neither the compressor nor the freon. It will run for a while then quits pumping cold air.
I've played around a bit with it and discovered that when it quits it corresponds with the 'Econ' button lighting up. If I set it to recirculate it will work again for a bit, then quit again.
It seems like the interval that it runs is getting shorter, but can't confirm that with exact times on versus off.
Anyone have this happen before? I am hoping it's a simple bad switch in the dash or something that can be replaced relatively easily....

 

Diagnosing AC systems as a home mechanic is not as straight forward as you might like. Do you have access to R134 manifold gauge set?

 

Unfortunately, no. Seems like I might have to take it to a shop. I know a shop that is reasonable with their rates but was hoping I might be able to solve this one myself....

 

If I had to guess, I would say the control unit in the dash is giving up. It should not let the econ light come on without you pushing the button. This may be what is turning the compressor off. If the pressure switch is going out on either high or low pressure, that will turn off the compressor but I don't think that would light the econ light.

 

I'll investigate that a little more on my own and see if I can come to a resolution. Thanks for the pointer.

 

Take it to a shop. It sounds like your evaporator is icing up. Not a terrible situation unless you let it go....

Bob

 

Just a quick update for you all: last week the Audi got whacked by a drunk punk in a pickup truck and totaled the car! The back end got all smashed in and the estimate to fix it was more than the value of the car, so unfortunately we don't have the car anymore, but that also means we don't have the A/C problem either....
Thanks for all the suggestions to fix it.