It's leaking from the AC drain hole on the firewall.That's where mine leaked from.The odd thing is that my carpet isn't wet. Still the heater core?
I believe it's a 3/4 and 5/8 adapter needed to bypass...correct?
You could try a stop leak product to get by for now.
My rad sprang a leak this winter and I threw in a stop leak product and it stopped the leak.
Too cold here to replace a rad so come spring I will replace the rad and flush the system.