Broadsword

Hi All, First time Jaguar owner. I have just got a 1997 XJ6 LWB 4.0 X300. It has 275 000 miles on the clock, I took it straight for an MOT and amazingly it passed! What a car! Pretty much everything works, but one thing is broken. The air conditioning. A quick check sowed the drive belt to the compressor was gone and the compressor pulley quite loose. Suffice to say it at the very least needs a new compressor. Using a Jag specialist is not an option. They quoted £600 to source and replace a non-genuine compressor, but that doesn't guarantee it will be fixed. I don't think they wanted the business. Does anyone have any experience of changing the air conditioning compressor theirselves? Access doesn't look too horrendous, but any tips would be great.