Where is the AC Drain? and what is the firewall?

There is a clog in my AC drain causing water buildup in my vent system of my '98 Ford escort (SE). I know that I can unclog it with a coat hanger or compressed air, but I can't find the dang drain hose. There have been postings before that have also mentioned the "firewall" What is that? I've opened the blower casing and empied the water. I'm coming pretty close to just drilling a hole in the casing and installing a plug-***** valve to manually drain the condensation off!