All work to be done by licensed professional. WE KEEP GOING UNTIL YOU HAVE THE INFORMATION YOU NEED, I come and go. This is step ONE.
Refrigerant boiling out of the oil when the compressor goes into a vacuum will cause the bottom of the compressor to frost up to the oil level.
That will only continue however until all of the refrigerant boils out of the oil
For that to continue, there has to be a flow of refrigerant into the compressor. that is through the suction line, if thats happening the suction pressure will not be in a vacuum
Tell me a bit of what you are doing, I can offer a lot more information.
The unit is not cooling. The low pressure cut off valve trips. High pressure is good. Just replace indoor TXV and LL dryer.