Hey All,
The air management control on our 1999 Ford Windstar (hey it was free) has developed a mind of its own. When starting the car, it chooses defrost mode no matter where we set the control. Changing the control setting gets no result. If driven long enough, the control will change eventually to the chosen setting.
I believe this unit is fully electronic with no mechanical linkages so there must be a "brain" in there somewhere. Does anyone know where the brain lives? This is one of those "see the dealer" Haynes Manual repairs if you get my drift. I do not want to see the dealer. Our local pick-a-part has a few of these minivans to choose from so I'd rather visit there instead.
Make sure its not vacuum controlled. Heaters are built to default to defrost when they lose their vacuum supply. Safety, you know.
It may very well be. I made my Haynes manual generality before actually consulting it 
If true, then I'm looking for the main vacuum source at the control, yes?
solfly
Reader
6/7/14 5:21 p.m.
i doubt anything that new is vacuum operated. it is likely controlled by a separate HVAC module or by the BCM
http://www.justanswer.com/ford/5qkhk-ford-windstar-van-1999-ford-windstar-heater.html
Vacuum diagram here!
Cheap tiny plastic line in the engine compartment seems to start leaking after a few years. Common on Mustangs, Rangers and Escorts...never owned a Windstar but I believe they may act similar.
Bruce
I'm beginning to suspect the control itself because the unit will sometimes change settings and start working on its own. Thanks for the vacuum schematic, egnorant.
Well, the controls are fixed. Because none of the modes worked, I deduced it must either be a faulty control or there was a problem with the vacuum source. Once I got the console apart, I saw how the control worked and realized it was fine. Also, I fired up the car and put the tube junction block up against my ear and did not hear a sucking sound. That left the source vacuum. Egnorant's schematic allowed me to trace the source (black) tube back to the control vacuum reservoir. Boy they did a great job hiding that thing. The inner and outer cowl had to come out so there was quite a bit of disassembly ( I already had the center console taken apart). When I eyeballed the reservoir, I found where the black tube teed into the reservoir /vacuum source line. The tube was almost severed completely which is why it would work very occasionally. Luckily, I could cut the tube back an inch and stick it back into the rubber connector. So the fix was easy but hunting down the problem was time consuming.
Thanks again for the vacuum schematic. The Haynes Manual picture was from an earlier model and had no relevance.
