1990 Nissan Payhfinder Air Conditioning Problem

I have an air conditioning problem with my Nissan. A couple of years ago I had the system changed over to 134 freon and it worked good for

2 years. I recently replaced the compressor after it seized up. The shop that I took it to performed all of the work and the system worked great for two days. After that is started to leak freon out of the service ports. When I took it back they said that it could be a couple of things. First the system could have a problem with the orifice tube or the expansion valve. My question is, does the Pathfinder have an orifice tube or an expansion valve. I have not been able to find an orifice tube anywhere and if it is the expansion valve could this cause the system to start leaking from the schrader valves? I don't see any signs of oil leaking on any fittings and have had it "sniffed" sevral times only to find the leaks on the schrader valves. One person told me it sounds like it is building head pressure from the orifice tube being plugged, another says it doesn't have an orifice tube. Both or supposed to be professionals.

Please help, it is hot in Florida and I am tired of spending money on a problem that never seems to be fixed.

Thanks,

Scott

Thanks for the follow up. My concern is that we have changed the schraders previously before the compressor seized and they are leaking again. On these systems is it absolutely essential to flush the system after a compressor seize or is just drawing the system down enough to get rid of any debris?? Would the compressor seizing cause the schraders to start leaking again?? I keep dumping money into fixing this problem only to have it last a couple of months and it seems like there is no end. Kind of frustrated.

I talked with another A/C guy and he said that ALL systems either have a orifice tube or some type of valve something like a PXV valve. That may not be the exact name but he tells me the system needs to be flushed again, new orifice tube and or PXV valve whichever it has and charged again for another $100. I am running out of $100 if you know what I mean

Any information is really appreciated.

Scott