water coming from outlet on firewall

Maybe you're looking at the inlet/outlet to the heater core? This is the only thing that would be in the firewall where coolant would come out. Is it an open outlet? Because it shouldn't be. There should be heater hoses on the inlet and outlet of the heater core.

It is your drain box under dash,it has a drain out of the firewall to let water form ac out.Now that said,your heater core is bad,and leaking that,s where your fluid is going,replace heater core.