Ford’s popular Taurus and its sister the Mercury Sable, with 9,632,293 vehicles sold is still a very popular used car.
It was designed with a bypass line around the heater core, which limited coolant flow through the heater core and regularly caused the heater core to plug. The #1 Symptom is no heat.
One pint of Irontite Thoro Flush will clean, unplug and restore a heater core to a "like new" condition. A single flush with ThoroFlush following the product instructions is typically all it takes. ThoroFlush is heavily used across the Northern States to remedy plugged heater cores and bypass lines in the Taurus and Sable.
ThoroFlush from Irontite is available in most major parts store chains. If they don't have it sitting on the shelf you can request it from the counter sales person who should be able to pull it from their distribution warehouse in short order. They may have to find it by part number. It would be one of two different numbers. (468-9110-16 or 9110-16)