Guys,

W220, S430 of 2002.

Not bad, MB plastic service cap basically can withstand like 200 PSI of pressure.
This service cap is a 2nd layer of safety when you valve core is leaking.

Below is HP port .


.
My both LP and HP service port caps re-newed already this year and so are the valve cores.

it helps slowdown valve leak and keeps 100% all dust out of the service port -

Imagine trying to clean that cavity with a toothpick with your face right next to 180PSI refrigerant

​​​​​​What method/tool do you prefer to renew your leaky MB valve cores ?

To replace that leaking valve core, no choice but to recover from the healthy side, the LP port, while at the same time calibrating the weight of the refrigerant too during refill.
This is an old car and should have lost R134A on its own normal leak, if from 2002 to today, easy 200 to 300 grams. This is a 950 grams system, 7 piston variable displacement Denso compressor.
I will put running 1-2 psi of nitrogen when replacing valve core after recovery completed, that way no ambient air can enter the HVAC system. That is what I did for my E400.

The oil color of this W220 looks very aged, very brown, to be expected.
I told my friend the owner, if he wants a good super well done vacuum evacuation, bring it to my house as these OLD cars need 10 hours to be good enough to dry to 350 microns when and if possible.
But his filter drier has to be replaced too.
Hell, at this age, I would replace all the hoses and o-rings...... its just a time bomb waiting to fail.

The engine is M113 and dual spark plug. Cylinder 7 is misfiring.
The HVAC display screen is so small and old fashion calculator display type LCD and has gone dark.....
I really feel sad when one decided to keep a 20 years old car without proper 12th year major rejuvenation on components we know will fail with age, I mean the known ones.