A/C Gurgling

What is your question?

When the A/C is on I hear an irregular gurgling/knocking from behind the dash, more towards the passenger side. First thought would be the drain tube is clogged, this is not the case, it was clear. I blew through the tube throught the bottom of the car, that was clear too. I fished a cable up into the tank, but didn't come back with any gunk or anything. I'm not sure where to go from here.