1992 Cadillac Deville A/C vacuum

yes you can pull a vacuum with low side this may have been half assed converted to r134 if that I why you see the high side the way it is it should have a Schrader valve

You know I don't notice it until tonight but the high side port does have threads on the outside. When I try to put my manifold gauges on it the my hose is to big for it. It just swallows it. I have never seen anything like it. Their is no schrader valve in it though. Their is like a small black round thing that sits at the bottom of the port and is pushed sideways instead of laying flat. When I take the cap of on the high side cap off you can hear something leaking. But I know the system is completely empty. Maybe it is oil or something. I replaced the low side schrader valve and nothing came out so it is weird. I know these are R12 ports because we have owned this car since day one. I know cadillac changed the compressor out the first year we had it. It was a defective compressor. Is their a way to somehow change the high side port out and make it an r12 port. Or can I convert the port to R134A and just use the couplings I have for it and still use r12 refrigerant. Thanks. It looks like the high side port just screws out.

GM made two different size ports int eh later years so people wouldn't hook up the r12 and try to charge to the wrong port there is an adaptaer for the smaller ports but not knowing what you have I couldn't tell you. the different size poerts had Schrader valves as well.