If it's leaking on the inside of the van, it's a leaking heater core. Not such a bad job to replace on a Windstar.
If leaking on the outside / engine compartment, most likely to be a bad hose. Do some up-close inspections with a flashlight to trace anti-freeze trails back up to the source.
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There are numerous possibilities. You really need to have the cooling system pressurized to determine what is leaking.
Heater hose or heater core.
hater core is bad
Does it smell like antifreeze? If so, it is most likely a bad heater core, or one of the hoses feeding it.
Sounds like heater core is leaking and what you are seeing is antifreeze
the most common cause would be a stuck closed thermostat.
Having it on "PARKING"
A blown head gasket.
it has a bad rear heater core
would a cracked blocked cause a car to bubble antifreeze inside the reservoir of a 97 ford taurus ?
Your door lock actuator is faulty and needs to be replaced
vacuum leak