Liquid refrigerant charging of a system is normally accomplished in the liquid line. For example, when a system is out of refrigerant, liquid refrigerant can be charged into the king valve on the liquid line or receiver.
FYI most refrigerants already have oil that is proportionate to the amount of refrigerant in the can. If you are using straight refrigerant and all you need is to add oil to your system, then there...
There is a test kit you can buy at a refrigeration distributor that allows you to capture a refrigerant sample. With this kit you can tell acid levels and moisture content. You need to know what...
You will add the R-134a thru your low side port. You will need a gauge to check the PSI level when filling. (You do not need the Manifold gauge set). There are a lot of all in one products you can...