The E3 code is a low voltage fault, because the air conditioning pipes are done inside the ceiling,

Basically, it's difficult, unless the leak is just near the repair port, first of all, you are sure that it is a copper pipe leak, not a main engine leak, and then the copper pipe is suppressed, go to the room to listen to the sound! If you're lucky enough to hear the sound, just cut it, and if you're unlucky, then knock on the top, there's no way.