1997 Ford Aerostar Q&A
1997 Ford Aerostar Question: Why is the Defroster/Vent blowing cool air with heat control full on?
Confirm that both heater hoses are hot to the touch, that ensures good coolant flow through the heater core, and if that is OK, then you may need to repair the temperature blend door and/or its actuator. The blend doors are known for breaking where the actuator connects to it. - cardocIII