What are the symptoms of a heater core going bad - and how to flush - in a Ford Windstar?

Smell.....when you turn on the heater, it smells like radiator (anti-freeze) fluid. Windows fog up when you hit the defrost, and the smell (above) is there. The inside Windows have a film on them when they are dry. Carpet is wet? Radiator fluid low (this is a late finding - you're loosing way too much fluid if this is the case). A plugged heater core would cut off heat to the cabin.

NOTE: this is the same symptom as a very common failure on the Windstar, that being the blend door actuator motor. See "Related Questions" below for more about that.

Personally, I have used the local quick service / oil change outlet for this on my Windstar. It doesn't cost too much - $50-60 maybe - and ensures a thorough cleansing of the system.

There are cooling system flush kits, Prestone being the most common on the store shelves, that have you cutting hoses to insert a garden hose connector. I have used them in the past, but I just couldn't bring myself to cut the hoses on my Windstar ;)) Another approach to flushing the core, is to remove the heater hoses and run the garden hose through them - that would specifically focus the flushing action on the core itself. And best of all: no hoses have to be cut...