Drain Tube Location

I have a 1992 chevy s10 pickup..4.3 litter..I would like to know where my drain tube is located.for my air cond,heating,defrost..I have a leak inside my truck floor and it may be my drain tube stopped up..please help

I have the same problem with my 1999 Tahoe. If anybody knows where it is, or how to unplug it please let me know.

i had a 92 S-10 Blazer took it to a drive thru service and ask the service tech why mine was leaking inside he said it needed to be blown out so he use the hi pressure and shot air from underneath the right side where the black box that sits on the firewall. Hope that helps

look at bottom of firewall in engine compartment passenger side for small black hose usually with 90 degree bend