I need a new AC compressor. My manometer reading on the low side fluctuates high then low and the AC takes a degree or two off ambient, but not cold. Probably the flapper valves inside the compressor.

The problem I have is that I have the diesel and I am the wrong side of the Atlantic. I'm actually in the Dom Rep, but I usually purchase most of my spare parts in the US and have them shipped here. The diesel RRs are very rare in the US, and hard to find parts for. So I'm trying to cross reference the AC compressor for the 3.6 TDV8 which are abundant in Europe. I have found a few references that it's the same part for the Audi Q7 and some BMWs, but I'm not 100% sure and of course I don't want to order the wrong part.

Looking at the photos, the compressor for the 4.4 petrol V8 for the L322 looks similar. Will it fit?

I really don't want to go to the main dealer, prices are stupid and lead times are very long.

I've had the same fluctuation with low refrigerant - have you recovered the refrigerant to see how much is actually in there?

I couldn't measure how much gas I took out, but I did empty the system, vac it and re-charge it to the correct value. No change. There is a local tech who reckons he might be able to strip and rebuild the compressor, but in the meantime I'm looking for a new one.

Ah, right - what's the high side doing? is it fluctuating too? if the high side is 'high', it's possible it's the thermostatic valve has jammed or there's a restriction in the filter-drier venturi, I've seen both these problems but I've yet to see a defective compressor (ETA - on these vehicles) - not saying it's not, just that it wouldn't be the first thing on my list of possibles.

I don't know your level of competence so please don't be offended if I recommend the following links as a guide to pressure readings & causes http://www.agcoauto.com/content/news/p2_articleid/257
https://www.vehicleairconservices.com/page/gauge_readings

Well I can safely say that's the first time i've seen one of those fault - usually they operate due to upstream problems (thermostatic valve, filter-drier etc.) That's the first one (on any marque) i've seen jammed.