donbrew

A) looks like a Schrader to me, probably listed as "shop parts".
B) $100 A/C service may be cheaper than blindly changing parts.... And causing your own blindness. High pressure chemicals can be dangerous, this from the fearless shade tree mechanic.

ChevyMgr

Maybe that part in the pic doesn't exist....

843de

Aha! A revised drawing, good 'ol GM.

ChevyMgr

The repair procedure does not include and evacuate and recharge, so you shouldn't lose freon, but you alread stated you let some out, so you'll have to perform one anyway.