Hi,

I might like to add to the prognosis that the orifice tube is plugged.
The high side pressure side would be going very high the more it gets filled up.
That could take a very long time to get filled up due, to the very short cycling going on, because of the restriction.

If you open up the line between the condenser and the evaporator, as it has a two nut coupling, you will find the orifice tube in there. It can or will be tight in there, so twist lightly back and forth while pulling on the colored plastic screen assembly.
The color helps to identify the size of the orifice.
If you find a fine gritty oil soaked substance in the screen that will be the blockage.
You might get by with cleaning it but it's not recommended and they are only about $7.00 in USA dollars.

On these older cars, it can be most likely that the desiccant package or bag could have busted open and the desiccant has dispersed.
This bag is in the big aluminum can that will have to replaced as a whole unit. They cost around $20.00 in USA dollars.
Compare the type of threads on the cans fittings carefully and their orientation to your systems connections.
It's not unusual that hoses change from vendor bidding on contracts to match other suppliers contracts with design alterations.

I suggest cleaning out the whole system with a flush as that stuff is everywhere and hopefully has not damaged the compressor.

There has to be a price to be paid to stay cool!
Imagine what a refrigerant free system, using big semiconductors, might be as an option $$$ on the electric cars of the future.
Be happy with a $50 - $300.00 do It yourself bill. Whoops that's on the 240's.

Phil