Water comes out of bottom vents, need advice please

[JJEH]

My '03 1500 SLT (4.7L) has water coming out of the bottom heater vent on the passenger side as well as on the passenger dash vents. I can see the water running out on the bottom and the windshield as well as passenger side window are getting foggy as soon as it's a lil bit humid outside.

Now, I was reading about a clogged drain pipe? Where is that located please?
I hope it's not the heater core, so I want to check that possibility first.

Any help is appreciated!

 

[HolyRamBatman]

Should be on the passenger side firewall.