I unfortunately have a 99 Taurus with a partially plugged heater core. It lets just a little bit of lukewarm air through. Is there a way tounclog it without removing it? The cooling system has had some sort of muddy looking substance in it since it was bought new...what is the purpose of this? Is it some sort of stop-leak or something? Also, what all would I have to do to switch it back to the regular green anti-freeze? Is this a common problem with the Taurus? A lady I work with has a 99 Sable, roughly the same mileage, (79000), and hers has a similar problem. The door is operating fine, the thermostat is new, so all it can be is the heater core, right?