can not locate ac freon leak.

[Dead Parrot]

I have had good luck with the R12 version of this: https://www.autozone.com/a-c-chargin...2oz/370967_0_0

Replaced a compressor in the mid 90s and used one of those cans with oil, leak finder, leak sealer and freon. Only needed a couple of cans since until something failed in the back of the compressor a couple of years ago. A large oil stain implies something that exceeded the capacity of the leak stop to fix. Planning on doing a Sanden conversion at some point.

Might be worth a try of the R134 version.