Topic: 67 AC line check valves

[67gta289]

I'm working on the high pressure line check valves, of which there are two.  In picture 1, the illustration calls out very clearly basic part number 19B596.  The service part number is C1SZ-19B595-A "Coupling Assy - Self Sealing" "External - male - includes check valve".  Yes, the diagram refers to 596 while the service part is 595 - refer to picture 3.  An NOS one is shown in picture 2.  I've used yellow highlights for this item.

This mates up to a second check valve which threads into the sight glass end of the high pressure line.  I've identified this item in aqua highlight.  This component is not called out, so I'm assuming that it might have only been included as part of the high pressure line 19837.  Can someone confirm this?

While it is neat to have the NOS 19B595/6 part, I don't feel comfortable reusing the other check valve.  NPD appears to have this item, identified as 19B596-1A, so I'll probably go that route.  I'll post pictures comparing them.

[67gtasanjose]

My theory on these valves are simply that for assemblyline purposes, the freon was already charged into the condenser/dryer & the evaporator/expansion valve/hose assemblies with the compressor also pre-charged.
These valves function as check valves ONLY while separated from their adjoining fitting. The manual charge valves, when opened 100%, also function to retain any freon charge in the compressor.

Bottom line, the "check valves" are useless, once installed in the operating system since they likely will not ever be separated in a "charged" system...we now evacuate the freon for any service procedure.