The Port (Schrader Valve) that is used to "Charge" This A/C system is on the
LOW Side [Larger in Outside Diameter] Hose.
Do Not Attempt to Charge from the High Side Hose.

I'm gonna fall back on CR from Texas's suggestions.

A/C is a "Building Blocks" kind of Endeavor,
You CANNOT "Non-Georgia Tech Engineer" it.

AND from reading your posts,you're a "Short Cut" Kinda guy...

And "Short Cuts" in HVAC work always come back and Bite You in the Nether
regions!

__________________
'84 300SD sold
124.128