You might want to check all the electrical connections. I remember when Herb (BroncoHauler) had a similar issue that seemed to be low coolant but wasn't.
I had a similar issue and also found an unsecure connection.
Worked for a while after I fixed that.
Now it runs and I have messed around with it quite a bit and can’t get it to cool.
I also don’t think you can add refrigerant to it economically.