A Ford Taurus heater core may become clogged, begin to leak or become damaged by the engine moving around too much. It also may malfunction due to a thermostat issue or heater hose problems.
A failing Taurus heater core should be suspected when there is coolant leaking under the dashboard, the windows fog up and there is a sweet smell inside the vehicle. A clogged heater core may need to be flushed or replaced.
Heater core connections can be damaged by ineffective engine mounts. In this case, the worn mounts may need replacing.
A malfunctioning thermostat may prevent the engine from reaching its desired operating temperature. If the thermostat's gauge is indicating lower than it should, then the heat level is lower than it should be. A new thermostat can correct this problem.