While looking for some front brake pads documentation in my large XK8 manila folder, I came across some notes I took in September 2012 involving how to check the integrity of our HVAC systems. This may prove to be beneficial to those who currently have issues with theirs. My notes read as follows:

Press AUTO and RECIRCULATE together while turning on the ignition, then release and press AUTO again.

If there are no HVAC faults, the display will show 00.

If there are HVAC faults, the display will cycle through a series of numbers which are fault codes.

To clear the fault codes, start the engine, then press REAR DEFROST and the "Arrow to Face" button together. Any displayed fault codes should clear to 0.