15.0 liters ( 15.9 quarts ) according to the 2001 Ford Windstar Owner Guide -
cooling system capacity with rear heater
Once a heater core starts to leak, the only remedy is to replace it.Luckily it appears to be a pretty straight-forward job on the Windstar - the heater core is at the bottom of the center of the dashboard - remove the ductwork and some of the trim pieces to expose the heater core compartment.Of course, this is after draining the engine coolant and disconnecting the heater hoses in the engine compartment.See "Related Questions" below for more...
What color fluid?
you must have low coolant or a bad heater core
According to the 2001 Ford Windstar Owner Guide : ( Motorcraft MERCON-V is used in the automatic transaxle / transmission )
32.75 quarts ( includes the heater and 5 quarts in the coolant reservoir )
Feel the heater hoses in engine compartment if one is hot and other cool try flushing heater core.
Did you ever have a coolant leak?
Maybe the heater core is leaking.
coolant level could be low not letting it circulate through the heater core, causing it to blow cold. Also, if the coolant level is low it will in turn overheat.
Yes, A bad thermostat can keep the hot coolant from reaching the heater core... also, low coolant levels or a clogged heater core can make your heat stop working.
Low coolant in the system. Defective heater control valve. Clogged heater core.
Low coolant? Bad thermostat? Heater core plugged, restricted or airbound? Bad heater control? Water pump not circulating coolant?