[s-cars] Engine Management shuts off AC?

[Toborg Michael (AC-SM/ESC3) *]

Still sweating in my 95 S6...
Used diagnostic channel #52 yesterday to try and figure out why the AC
doesn't work, and I got segment d3 to light up. Bentley says this is
"Engine management system" It pretty much turns off the compressor as
soon as it comes on. When driving I can feel a slight hesitation when
the compressor cycles... The electric fan seems to be working fine.

So what does this code mean? What part of engine management system is
shutting off the AC?
I gues a VAG tester might be the next tool to use...  

Thanks!