What reason do heater core stop working?

Hello, Dave here, contributing to RepairPal and providing expert advice since 2010. Is the concern that the heater core is confirmed to be leaking? To be honest, there is more than one reason you could have a wet floor! Has the heater core been pressure tested and verified to be leaking? I would do that first; pressure test your cooling system to verify what the concern is. Verify you do not have water from an evaporator hose that is misrouted or plugged. Verify the wet carpet smells like coolant -- not water. It does sound like maybe a heater core is leaking -- in which case the only repair is to replace it. Seek help at a shop near you -- https://repairpal.com/auto-repair-near-me Click the link or call us at 877-913-1554. We'll gladly find you a certified RepairPal shop in your area.