The heater core went out. Water leaked out underneath the car and some inside on passenger side at foot space

Whenever I see a system which is leaking from more than one or two places, I do a head gasket check because that tells me that the system is experiencing above normal pressures. the wet floor is a heater core. whether it's a water pump or some other thing near it only you can tell. Actually it rarely happens, but the wet floor could be the hose where it meets the heater core at the firewall; again, only you will be able to tell the difference. if the hose connection looks dry, assume that it is the core itself.

Your water heater core is beginning to leak. Eventually, you will find an antifreeze puddle on the passenger side floor which can eventually lead to the rupture of the heater core and a large amount of antifreeze in gaseous form within the cars interior.

It is time for a new heater core. Should you want to go the cheapest route, you can purchase a bottle of copper plugging agent. Ask your local car part guru what he has to plug a leak in the heater core.

Be forewarned: should you go this cheap route, you risk clogging your heater core for good and you will no longer have heat until you replace the heater core.

With the location of the water leak and the cold air, it sounds as if the heater core is leaking or one of the heater hoses going to or from the core has a hole in it. The heater core is on the passenger side of the vehicle, inside, against the firewall. Is the carpet wet underneath on that side?

Have you been adding any coolant? You could have a leaking heater core, which will usually leak to the inside, wetting the carpets in the well. Most American cars locate the heater core on the passenger side of the firewall, so a leak will typically show up on only the passenger side floor. I once had an Audi that had the heater core mounted just about dead center on the firewall. When it started leaking, both sides of the well(s) got wet.

Your heater core is leaking, and when it does, it drains into the foot well passenger side. Best case would be a hose that is leaking, worst case is the core itself. Replacing the core is a big job.

To be honest, most mechanics hate replacing heater cores because of their location. They are usually on the firewall on the inside of the car underneath the glove box under the dashboard and behind a plastic black cover. If you look under the hood at the firewall on the passenger side, you should see on inlet hose and one outlet hose which should be replaced along with the heater core. They must be removed first before you can remove the heater core. Basically you have to lay on your back on the passenger side Front) floorboard, remove the necessary panels to get to the cover, remove the heater core and install the new one first, then intall the new hoses, reinstall the cover and any panels you removed. Lastly, be sure to bleed and top off the coolant while you run the heater, then check for leaks

What about a leaking heater core... If the defroster is on and your winshield fogs up temporarily when the car is first started, that is a good indication of a heater core thats leaking water inside the car... Have that checked, Im guessing its your problem..

Two things: If there is a stickiness or sweet smell to the water, your heater core may be leaking.
If this is just a summer thing, your a/c evaporator drain tube my be blocked/clogged or leaking inside the vehicle.

sounds like it may be a heater core check your radiator fluid to see if its full and see if the water inside is water or antifreeze if it is antifreeze its a heater core.

Is it antifreeeze from heater core or heater core hose leak?  Is the leak pure water, or maybe something else?
Put it in the garage again overnight with an old white towel in the drivers foot well, best if you can find a way to stretch it from drivers seat forwar to firewall and keep it off of floor mat.  Check it before you go to bed,  then in the morning if no leak found yet.  see if the color/location of the spot helps you identify the source.  I think the heater core is under the dash center.  Anti freeze is green/yellow or orange.
good luck