Ok thanks the 1 thing I forgot to add is that when I first start driving it will just about coolenough but after about a half an hour it’s not very cool at all
You have just enough freon in it right now to cycle the compressor clutch. When it kicks in and starts pumping the freon, it sucks what is left in the freon well dry and it throws out the low freon switch and disengages the compressor clutch.
Then it sits idle for a bit, the freon equalizes out and goes back into the low side reserve. Then the compressor turns back on again and pumps it dry and shuts down the compressor again. Repeat, Repeat, Repeat...
Put another can of 134 in it, an watch the Meat Thermometer in the cooling vent come into the 50° range. Then stop adding freon.
Lots of early AC systems have a site glass on the Reciever Dryer. If you see bubbles in there, that tells you your system is low on freon.