Check your coolant level. It may be critically low.
thermostat stuck
The most common reason the heater is blows cold air on a 1999 Ford Winstar is a bad thermostat or blocked heater core.
See "Related Questions" below for a complete discussion on possible causes and more importantly: fixes
you need a new heater door actuator motor about 50 dollars from ford.For a comprehensive review of Windstar "no heat" problems, see "Related Questions" below for more
you have a short in the wires for your dash and lights So what do I do to fix it?
This sounds like an issue with a fuse. In newer sunfires, if the Radio/ACC fuse blows, no indoor lights work and nothing will turn itself off when the car is off (meaning your daytime lights will stay on even with no key in the ignition). It's a 20w minifuse, walmart sells a pack for about $3.50.
Heater core changed three years ago,I changed Thermostat Heater still blows cool air.
can you please clarify what you mean, do you mean that the front heater blows cold but the rear blows hot or do you mean that when the heating is on cold it blows hot? many thanks paul
most likely a blown fuse, replace, if it blows again you have a short, if you have a trailer connection look there first
the heater blows warm air when fan is on low but blows cold air when fan is turn to higher setting
Get the air out of your heater core.
The heater fan ONLY blows the air, it does not make the temperature of that air. Your heater temperature controls how hot the air is. Adjust your heater temperature for hotter or cooler air.