why passenger floor floods when air on

You may live in a place where trees drop a lot of debri and that stuff works its way into the HVAC housing and stops up your drains. Blowing the drain tubes out may be a temporary fix because it just pushes the gunk back into case and afer a short time it gathers back at drain area. Short of removing HVAC case to disassemble and clean may be only lasting solution. May try to remove drain tube hose and probe carefully with a tool in housing drain to try and pull debri out.

YOU EVAP FOR A/C DRAIN IS PLUGGED