Need help with AC diagnosis.

Maybe someone saw this kind of issue. No cold air at all, on very rare occasion there is cold air for few second mainly just after very hard braking but not always.
No errors reported in techstream, compressor speed control working fine, evaporator temperature is same as ambient temp, pressure with AC off is around 0.5MPa on both sides, when start AC, set temp to LO, low side drops slightly to about 0.4MPa and high side rises just above 0.5MPa. Then randomly low side drops to about nearly 0 (but never goes in to vacuum scale) with high side slightly going up. It stay this way for a second or 2 then is going back to default as previously. I see 2 possibilities: Compressor or expansion valve, more likely valve issue. Any way to verify what is wrong? You can see poor quality video of pressure reading with pressure drops at 15s , 1:40 , 2:53 and 3:55

 

I'm trying to prove valve fault, to get access to it (and cut capillary tube to force it closed) have to remove blower assembly, but it seems impossible without complete dashboard removal. Seems to be cheaper sell it and buy another car with working aircon.

 

Finished diagnosis, compressor faulty, when punctured valve top "hat" and forced it close, low side went in to vacuum, then periodically pressure raised close to high side pressure. This can't happen when valve is closed. That mean compressor is "leaky" and looses pressure, also high side was only about 7kg/sqcm. With manifold simulated evaporator I was expecting it to be really cold but nothing like that. It was colder than ambient but not what expected. So compressor is not making proper flow. Probably destroyed good expansion valve and needlessly dismantled cabin interior.
Any opinions, I'm wrong with anything?

 

Never saw any, maybe there is something on youtube. Replacement itself is very simple, but preparation and gas refilling require some additional tools and materials.