Well, the stuff is getting into the system just fine, it just isn't staying in the system like it needs to, IE, the pressure builds up, the compressor starts to run, and then it shuts back off immediately, and a high pitched sound can be heard as the pressure drops back down to nothing. Already wasted one of those really big cans of r134-a Meijer sells with the re-usable gauge into the system, and it must have just gotten expelled back out into the air. Might try to get some of that stuff with the UV dye in it, and the special light and glasses to look for where the leak is coming from. I know the general area it's coming from though, because I remember when the Valvoline shop down the street tried to charge it, they got it running nice and cold, but then the stuff all shot right out at once (quite visibly, and was a pretty disturbing sight to see) and it was coming from the area where the compressor is located on the Neon.
I'm wondering if the compressor itself may be damaged, as it's a possibility, because of the incident with the engine mounts, and the pothole, and having to get a new engine because of it. It's possible that part of it may have hit the ground as well, because three of the engine mounts were bad (read: Broken) at the time, and the old engine was sagging BADLY, as was the compressor. Is it possible for it to be cracked open, but still able to turn on and run for a few seconds/minutes/whatever?