The first thing to check would be your coolant level. If the level is low, inadequate heat will result. I suspect however, that you have a temperature blend door actuator that may be inoperative, or a blend door that may be broken. If you remove the radio, the upper most corner of the actuator is visible. Often the actuator will offer a "tick tick" sound if faulty. Removing the actuator may reveal if the door shaft has broken.
I have a 2003 windstar piece of junk...going to replace the blend door actuator for the 2nd time. Its available at any auto store for around 33.00. the little worm gear on the motor shaft breaks a tooth or two because it is plastic not metal like it should be.
I restored heat to my wife’s 1999 Ford Windstar (Don’t ever buy one of these) over the weekend by cutting into the air plenum beneath the dash and propping up the blend door (with a 3” bolt also drilled into this plenum) whose connection to the actuator motor and shaft has failed. I benefited from a Youtube video by Heatertreater.net which walks you through this process. The Ford garage told me that in order to replace this blend door, I would have to purchase an entire replacement air plenum including a new heater core and air-conditioning evaporator core that go along with the plenum just to get a new blend door which is permanently enclosed in the plenum. Parts: $469.00 (Not including any labor!). I saved a lot of $$.
Before you go through the incredible hassle of pulling the dash to access the heater box and blend door. Make sure you check the blend door motor first. It's attached with 3 screws. Mine had a busted gear inside that gave the exact same symptoms as a broken blend door. So yeah, check the easy stuff first.
I just went through this one with our 2002SE.
1st: beware that the auto store part may not be the same as the one in the car. (NAPA's was not the same)
2nd: the stereo has to come out because the blend door motor is right behind it. So, you need to get the Stereo Removal tools: a pair of U-shaped springs "kit", very inexpensive from your parts store. Push them in smoothly until they stop; then apply pressure to the outside, as in with your thumbs and the spring clips will release. Pull out the stereo
3rd: be mindful of the antenna lead
4th: I would suggest removing the lower valance with the CD drawer if you have it. The 2 screws on either side can be a *****: #1 Phillips and you will probably need to get something behind them to pull while twisting. Then, don't put it back on until everything is back in place and tested for operation. I guarantee that if you put it back too soon you WILL drop something down in behind it. :incazzato:
5th: Wish I had seen Poppy's excellent suggestion about using a long flat blade to get the ash tray out first; just left it in and when #4 happened it got in the way.
6th: I had to use a 1/4 drive with long extension(s) to get to the bolts holding the door motor. There may be some interference from a wiring bundle just above it. There is only one wiring connector to the motor.
7th: the peg that goes into the plenum to drive the door is shaped and will go in only one way.
8: Reverse the process. At which point you will say, "Dang, that was easy".
You did put the lower valance back on last, right? :ihih:
Great info, guys. On our 02 Cargo, I just replaced the blend door actuator with a new one from Kragen/O'really, and the motor cycling is gone. It was a bitsch to access the actuatior until I took the entire bezel off. There are two screws at the top you can access after removing the radio, and two at the bottom, visible behind the cupholder. A flashlight is your friend here.
In typical Ford style, the screws holding the bezel have 7 mm heads, and the ones holding the actuator are 8 mm. To fix a Ford, you need every tool in your garage - plus one you have to borrow or buy. I thought it was only modern Fords, until I bought a Model T. On all pre-1949 Fords, you have to drop the rearend to lift the radiator cap.