Sounds like the heater core may be plugged up or the heater damper door is broken.
See "Related Questions" below for more
Temperature is controlled via an electric actuator motor.See "Related Questions" below for more all about Windstar rear heating / cooling systems.
For a Windstar, a common problem is a failed temperature blend door motor - actuator. See "Related Questions" below
The blower on the back heater may need to be replaced on the 2000 Ford Winstar.
If by "heater box" you're referring to the heater core, we've got you covered with the "Related Questions" below.Be sure to review the questions regarding the blend door and blend door actuator motor - other very popular heating/cooling parts in the Windstar
The most common reason the heater is blows cold air on a 1999 Ford Winstar is a bad thermostat or blocked heater core.
Suspect a plugged up heater core then.See "Related Questions" below for more
it's leaking coolant. Needs to be replaced.
The temperature actuator motor controls the flow of air through the heater core. The motor is located under the driver's side dash, above the transmission tunnel. It's a little difficult to get to, but not bad. Check heatertreater.net for pictures and what to check for on the actuator motor.
Not a whole of symptoms to work with here...The most common cause of "... heater not working..." is a failed temperature blend door actuator motor.See "Related Questions" below for more
There are 3 primary questions about Windstar heating & cooling problems: * Temperature blend door actuator motor replacement * Heater core replacement * Various causes of 'no heat' problems See "Related Questions" below for links
Could be, Low on coolant, A stuck open thermostat, A plugged heater core, A faulty temp blend door actuator,
heater core plugged or air locked check to see if hoses going to heater core are hot