Can anyone tell me definitely where the low side service port is located on a 1990 245 wagon. The manuals have conflicting information. Some say its on the receiver dryer, but that looks like the high side of the A/C to me. Other manuals say it is on the back of the compressor, which of course is very hard to get to. I think the 1990 was a little different than both the 89 or the 91, but I'm not sure. Any help from someone who has had this problem? It's an R12 system still. Thanks!