As the title says, all the r134 refrigerant leaked out. Evidently, it leaked from the high side hose that houses the schraeder valve at the junction with the next hose, just above the where the upper radiator hose attaches to the radiator. I can even turn the hose by hand easily 90 degress in each direction. I assume it is not supposed to be this loose. Is it likely just the o-rings that need to be replaced? And, is the hose just pressure fit to the one it attaches to? Does the hose just pull off?

For reference:
Refrigerant Hoses-3.2/4.0 Litre - Parts For XJ6 & XJ12 from (V)667829 to (V)708757 | Jaguar Heritage Parts UK

Hose part #CCC3777 number 17 in the illustration
O-ring #'s KSR110002 and KSG111116

 

I'm assuming this is the connection to the condenser we're talking about?

As I remember, the fitting can be rotated (slightly) as there's just a barb fitting with a plastic collar and 2 o-rings in there ..so yes, it does just "pull out" after you release the big nuts. Mine rotated there too but it wasn't the source of the leak.

I wouldn't just assume that this is the primary source of your leak. It could be of course, but if I were you I'd check the system in darkness using a UV lamp and look for dye trails before replacing anything.

good luck!

Larry