Which valve do I add freon to upper or lower? on 1999 Cadillac Catera

Need to add freon . There are two ports, one on top nearer passenger Compartment and one lower nearer to radiator. Which do I use.

Asked by for the 1999 Cadillac Catera
1 answer 1 comment
I would not add any refrigerant if you are not familiar with a/c systems, take to a shop with the correct special equipment to do the job correctly, you can't just FIX a/c by JUST adding refrigerant.
Well, freon can certainly be added if the system is low and fix the cooling problem if that's what the problem is.