Help! Shaking at idle when A/C is on

[Sauci]

This is somewhat of a continuation of another post.

Long story short:
I have a 2011 A5 and about a month or two ago I started her up and the thing started shaking like crazy.

Symptoms:
- Intense shaking at idle when in R, D, S.
- Only when stopped with the brake engaged.
- Seems to almost completely go away when I turn off the AC. (Relatively new development. Before doing the repairs below, it shook less with the A/C off but still definitely shook more than it should.)

Attempted Fixes:
- A member suggested the exhaust was touching the body. Checked that an no luck.
- Took it to the dealer to get a recall item fixed. Asked them what it was they said it was the motor mounts.
- Bought new motor mounts and had them installed. Still shaking, but shaking slightly less.
- Independent shop suggested replacing the PCV and after doing some research about what a failing ones symptoms would look like decided to change that. Slightly less shaking but still definitely there.

I've dumped around $1,500 into this trying to get it fixed and it's killing me that nothing is working. Based on the fact that this issue seems to go away when I have the AC off, I'm leaning towards something in that system causing it but I honestly have no idea. Please let me know if you have an ideas.

[TTRStud]

You've touched on all the points that I was going to recommend checking. Not sure if the AC compressor's pulley is not rotating as freely as expected, or maybe the bolts that hold the compressor in place may have come loose - so when the compressor clutch engages and puts more resistance it causes it to vibrate? Just speculating here. Hopefully you'll find your fix soon!