I might have answered my own question...looked in my GM service manual and I am using the correct port (lowside). Only problem is I can't seem to get it to take the freon very well and the gauge goes nuts!! I have read several DIY sites on performing your own A/C maintenance, they state it is not neccessary to flush and vac the system but recommended. Apparently the Aurora has a replacement service tube now that will take the debris out of the system, but my compressor hadn't completely died, I thing the bearing was the only thing going out, cold air still worked but with alot of noise. So I think if I follow some other directions as follows I should be just fine unless someone here knows different.
1. Put the first can in upside down
2. Put the 2nd can rightside up
3. Add PAG oil to system
4. Test for leaks
5. Fill the system full with 3rd can
Hopefully that works and I don't blow up the system cause the gauge that I have sure acts funny, goes nuts, when I add freon to the sytem. Let me know your guy's opinions.
One more thing, why and how can the highside & lowside ports be on the same line? That is the way they are according the the service manual unless I am missing something?
Thanks