Air Conditioner issue.. 'Tis the Season

Symptoms: AC was blowing ice cold. Sitting in a parking lot in 100f heat it started blowing warmer and warmer. Now it's just moving hot texas air. Obviously I'm assuming something didn't like the increased pressure and gave way venting my precious 134a.
However!
today I attempted to put in a can of 134a (straight up, no additives or oil) and it doesn't appear to be going in.
The compressor is running (or at least spinning) fine. I can command it to run at various speeds through techstream with no problems (and no codes or any problems reported by techstream, btw). The sight glass clearly shows no fluid. The high side and low side are pressurized. I need an adapter for my good manifold set before I can read pressures so no info on the exact numbers yet (sorry), but both are definitely strongly pressurized still. The can of 134a and cheap nozzle definitely are venting out, and when connected to the low side the car is definitely venting INTO the hose (I can see it puff up before I open the can). But when I do open the can it just seems like they are both equally pressurized and nothing is going in or out. Maybe it's just slower than I remember, but other cars I've topped off in the past empty fairly fast and you can hear it and feel it. I am seeing zero changes in the siteglass. I'm charging as gas, not liquid.
Questions: is the pressure still in the system a sign of either no leak or a small leak? I would think if there was a leak big enough to go from ice cold to zero cooling in a matter of an hour that pressures wouldn't remain so high 24 hours later.
Is there an over pressure release mechanism?
Is there a need to "prime" the compressor with a liquid charge first (obviously with the compressor off)?
Can the compressor spin like it's fine with no noise but not actually be functional for some reason?

I apologize for not having pressures, I'll get an adapter for my home manifold set soon, but I was desperate to try anything today and I only had about 15 minutes today to try something.

Thank you for any tips or answers.

 

ok. some updated info. refrigerant isn't going in because i believe the system is fully charged. i do see some liquid refrigerant in the sight glass, but zero movement with the compressor on. no one locally had 134a adapters 0r new hoses for my manifold (Ill try HF tomorrow). Ill get pressures but it vents liquid on the high side and gas on the low and while far from scientific it vents just as violently as it does on a known good system.
so.. compressor spinning but not moving refrigerant due to some internal failure?
something blocked or clogged?
I reallllly hope i dont have to get down to the evaporator

 

High 112
Low 90
ambient 72f
edit: this was with the compressor running, max cooling, fan on high.

I sincerely appreciate any advice or guidance.

 

New info:
Low side pressure (95f ambient) is 120psi with compressor off. With it on it drops proportionate to the compressor speed, but only down to 80psi.
High side pressure is 125psi with the compressor off and went up a little to approximately 132psi with the compressor running full speed.

Turning the compressor off both pressures went to 110psi

Compressor back on to full speed (via techstream): low dropped to 90psi, high climbed to 125.

If it was a clogged port shouldn't the pressure still climb to 200+ psi on the high side? If it was the compressor not working at all (despite spinning) the low side shouldn't be dropping proportionate to the compressor speed?

Are there any other numbers I could look at to pinpoint the issue?
Edit: I just saw your post Patrick, thank you. I'm leaning towards compressor as well, I just want to be sure as the difference between the amount of work between swapping a compressor or somewhere near the evaporator are so vastly different

 

Ive ordered a new condenser as a precaution as well. Mine is pretty gummed up and dinged from eight years of insect/pebble/pixie strikes. Denso brand, only $65usd on amazon. will pick up a compressor from a yard tomorrow morning and do the work on wednesday. Will update. I guess I'd just be happier if my compressor sounded like it had a catastrophic failure, so I wouldnt be guessing.. but it makes the most sense.

 

Update: Wednesday I put in a compressor from a junkyard, new condenser and drier. Everything is working great. It was a pretty fast job, the biggest pain was putting all the plastic back under the car to be honest. 6 hours total including several breaks when the skies opened up, kids rode their bikes, lunch, and and episode of Maron.
The problem turned out to be the condenser had a leak and I lost too much lube and burned up the compressor. Two quarts of EVOO and we are up and running.