So I have bought a lot of replacements AC parts for my TD. I plan on replacing everything but the lines, evap and condenser. I have 4 cans of R12 that I plan on using.

So my question is..
My TD has R12 in it already. The comp does not come on but I can hot wire the clutch and force it on, I assume it's low on freon. I can push on the shrader valve and there it defiantly still has freon in it. Should I try to ad some R12 to it or do a rebuild like I planned?

In the perfect world I would recover the R12 in it then check for leaks and service with R12. I do not have any way of recovering the R12 that is in it and I can't pull a vac with freon in the system.

Any thoughts?

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08 R320 CDI current

Past
95 E420
87 300D Turbo 5spd
90 300TE
83 300SD
85 300TD
92 400E
85 190D