Hello, can someone tell me which is the high, and which is low A/C port from this picture?

Is the low pressure green?

 

Yes. Just remember they don't interchange so you can't hook up the AC gauges backwards. Low pressure side is always the larger connection. Sometimes I will install blue and red caps as I don't understand why the factory wants to confuse things with black caps?

Now one caution? This is for R134a systems and somewhere in the 2013-2014 era Jaguar made both R134a and R1234 systems. The newer R1234 stuff does come with grey caps. I guess to differentiate it from the R134a connections?
Your AC tag is almost readable and I am pretty sure yours is R134a but it will say on the tag what refrigerant you have and the capacity of the system
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Yes, the A/C tag reads R134a. I read you can use R1234YF refrigerant as backward compatible for R134a? Is this accurate? Might you have any suggestions on the system to recharge it? Thank you for your help.

 

If possible I would stay away from R1234 unless the car came with it from the factory? Just not comfortable with substitutions. Also it's WAY more expensive!

Not sure what your asking but just the normal AC gauge set is all that's needed to charge the system.
I don't like the single connection with a can of Freon because you need to see both the hi and low side pressure when working on the AC. Plus if you want it done right you should vacuum the system down to check for leaks and then put in by weight the correct amount of Freon. I do like that my 2014 XJR takes exactly 2 cans so easy to do.

Far too many people and shops just keep jamming more and more Freon in the system regardless of what's happening.
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