Yes, the leak definitely sounds like a leaking heater core. Sometimes they are easy to replace, and sometimes they are difficult. You can try some radiator stop leak in the radiator but most of the time they have to be replaced. If you do it yourself, get a good repair manual from an auto parts store. It will have the instructions on how to replace it.
Passenger's side? Could be a leaking heater core
heater core is leaking.
Antifreeze will be leaking in the floorboard on the passenger side, there will be a smell of antifreeze through the vents.
Probably a leaking heater core.
If that water is engine coolant, the heater core is leaking.
your heater core is leaking i would replace it.
This would be caused by a leaking heater core, or a leak in the plumbing associated with it.
The heater core (a small radiator for your heat) is leaking, I would suggest a new heater core as they are about as cheep to replace as they are to repair.
Either the heater core is leaking or you have a leak at the windshield or the cowl. If the fluid tastes sweet it is coolant and your heater core is leaking.
It could possibly be the heater core Check your heatting and a/c
If your talking about coolant leaking on the passenger floor then it means your heater core is leaking and needs to be replaced.
I think it is your heater core gone bad