Yes, the charge on the AC was a tad low (several years old already and the system will never hold all of the charge infitetly, due to design).
With proper charge, both sides are cooling like a sonofabish.

Still have the error 353 but I assume I have to replace the regulator for that anyway (although I cannot detect any reasons why it would need replacement since I cannot see where the deficiency in blowing is myself - never owned a cayenne before so cannot tell, but seems OK to me).

 

All my money is on the servo for the mixing flap!