Hoping to draw on the collective wisdom of the FullfatRR community, so thanks in advance.

My car is a 2010 L322 facelift 3.6 TDV8 Vogue SE with approx. 139K miles. Bought the car back in December with a couple of small issues, one of which was a split AC hose - Part No: LR010889.

The car has been with a specialist in my neck of the woods (York area) for a couple of months getting these niggles ironed out, including fitting the AC pipe, testing and regassing the AC system.

This was done, the system held pressure the AC blew cold and I collected the car. A few days later, the AC stopped working. Back to the specialist to investigate this week and when they've gone to collect the AC gas its all gone! So, the system is filled with nitrogen and dye and out comes the UV light. No leaks can be found, nor can they hear the nitrogen leaking. Admittedly, they were short on time and didn't want to remove any bits to investigate it further. Nor do they recommend just "chucking" parts at it without identifying the root cause. For clarity, I'm not bashing the specialist here. They did this investigation FOC.

I asked how quickly the Nitrogen pressure dropped but they couldn't tell me as their Nitrogen system doesn't have a pressure gauge.

Their closing comments are that their is a "significant" yet unidentified leak. Its not something they've seen before on the L322 and they suggest getting it looked at by an AC specialist or chucking a condenser on to eliminate that (although they said they didn't have access to the condenser to fully rule it out for leaks).

So based on the above, what are the thoughts and recommendations? I've done a search of the site but couldn't find anything that specifically replicated my issue - although lots of AC related issues.

I do have a GAP IID tool - so anything I can check/log with that?