carfan87

I have a 1997 A8 which had a small AC leak (took about 2 years to leak out). Now the Freon seems to be leaking out in a few weeks or maybe the expansion valve is bad. I've had it to two shops that cannot seem to find a leak (unless it's in the car). I've been doing some research to see what it could be and this is what I've come up with.
Evaporator connections under the cowl (I assume this is inside the car?)
Evaporator (I hope not!)
The low pressure switch (I'd think they would have found the leak there)

The other thing would be the expansion valve. I suppose I'd have to have the system evacuated to see if the Freon actually leaked?

This is going to sound odd but lately inside the car it smells similar to a dentist's office. Might leaking Freon smell like that?

Anyone have any other ideas to check?

TSHong

Go to a shop that can put dye in the system to track the leak.

carfan87

It does have dye in the system and they still could not find a leak.

TSHong

Its bad news because you have to inspect the evaporator core and xblock, but if you have to take it apart you might as well replace both.