Decided to find which blend door actuator/motor was causing the bubbling sounds. Figured out which one it was and compared it to a spare recirculation door motor I had. Unfortunately they are different inside despite being otherwise identical. The arm would have been swappable but the potentiometer and gearing inside were different. On the off chance I gave the contacts a clean, popped it back together and replaced it and its working fine now. The casing just clips together, I can imagine Jaguar would almost certainly not go inside these to diagnose and repair these, instead just swapping them out.

 

Thanks for posting this, I also have the bubbling noise. I prefer to repair something instead of replacing IF it can come apart. Was it the potentiometer swipe traces that you cleaned? Do you use a special grease on the surfaces?

 

I do apologise for not getting back to you!
I cleaned the potentiometer swipe traces, I didn't apply any new grease which was a choice I'm not pleased with, however, I can confirm as of today it is still working perfectly