Well Air con packed up on my 3L TDI Avant so i went to get it checked. It had lost 2/3 of the gas so got it re-gassed, fired up the engine and black smoke started billowing from the engine bay. The clutch on the compressor had let go and it ripped itself to bits. Non Gen part from TPS is £756 +VAT!!!
I have got a reconditioned used one for £350 +VAT, but peoples make sure you get your air con checked every 2 years as the recommendations!!
It would seem it had been running on low gas for a while and when it was topped up and at the right pressure it killed the compressor!