I've just plumped down some cash for a 1kg cannister of R49 (R12 replacement) and a valve/connector to see if I can get the aircon working.
Yes, it will probably cost the same as getting a bloke out. Yes it will probably leak. Difference is, If I do it and it doesn't work, I can say f*ck it, and see about getting the aircon removed to save a bucket of weight. If a bloke comes and looks, and I pay for a pressure test, then a regas, then any repairs, because "It shouldn't be that pricey".
All I need to do is work out how much gas I need going in.
The compressor still turns OK, but won't kick in because of no gas pressure. The circuit still works.
Just got the cost of the gas to try, and these days, even halfords sell recharge/top up kits for modern R134 systems.