When moving things around, I noticed that there was a connector attached to the lower-bottom front bolt of the AC compressor (when looking from the front of the car). See picture attached.

There was no wire connecting to that connector.

Does anybody know what it is and whether it is needed?

 

I believe that gets a plug containing a fusible link. A/C should not operate without it.

 

The widget IS the fusible link, so to speak.

It's called a thermal fuse or thermal limiter.

It contains a fuse. If the Freon drops too low the 'superheat' switch at the back of the compressor grounds the fuse to break the power supply to the compressor.

You're right that the a/c compressor will not work with it disconnected.....unless it's been bypassed. Or, in some cases, the compressor is replaced with a different style that doesn't require it.....using a pressure switch system instead

Cheers
DD

 

Maybe there is something to it... That car was in a shop with AC issues several times... How do I know? Service records from the previous owner. I learned that dealers charge a lot of money servicing Jaguars by studying those receipts...