You have to have pressure to make the leak show up, so even if there is not enough to trip the compressor , there may still be enough to show on a bubble test.
Where the leak is and what is needed to fix it can not be determined till you find the leak..
Push the schrader valve in for a sec to see if there is still pressure and then try a soap test where you found dye...
If it's empty, forget it til you get some pressure back in there .
I just add a little refrigerant to get a few psi and go leak hunting...