I haven't done it, but I've heard there's a vaccuum solenoid in the rear box (down by the floor) that sticks.
Mine does this sometimes too, but not often enough that I've gone ahead and ripped the back wall apart. I can usually fix it by switching the rear control from cold to hot to cold to hot, etc. This, I think, loosens up that solenoid.
Maybe someday when it breaks altogether, or the kids start complaining loud enough, I'll fix it ;)
Good luck!
AnswercI have same problem on my 98 replace the temperature switch is the one of three in the middle of dash the one with red and blue sticker(is a vaccum switch)Answer
Change the rear cool/heat switch on the front panel, furthest on right. It's about $27 from Ford and easy to replace. Two screws and clips hold the face cover, 4 screws hold the panel in and one screw holds the switch. Remove the vacuum and electrical connectors.
AnswerYou probably have a faulty temp blend door motor assembly on the front unit. It is located directly behind the radio, way back in on the front of the heater case.Could also be the door inside behind that assembly is broken. The door lifts to allow hot air and drops to close to send cold air. I am in the process of fixing mine and it ain't pretty, but cheaper to get the assembly than to replace the door which requires the whole assembly to be replaced. Lots of luck with it.
You probably have a faulty rear temperature blend door actuator. Remove the left rear trim panel to access it. Be sure to review "Related Questions" below for much much more on Windstar heating/cooling problems
replace front heater corefront and rear have independent heater cores
There are separate expansion valves in the rear, so even if the front system is failing, the rear unit could still work normally.
think about it they have independent control thus they have separate cooling systems
The control for the heat on the dash has a control for the back seat and also has a setting that says something like "Rear Control". This allows the passengers in the back seat to control their heat independently via a temperature control in the back seat (on the back of the center console). So you could have the heat on in the front and the rear on "rear control" and if the passenger in the back has set their control to cold, it wold blow cold air in the back even though you have the heat on in the front.
Possible blockage in the rear air units expansion valve. I just replaced mine for the same reason.
If you have your system on heat and you are only getting hot air from the front vents and not the rear you might have a bad actuator motor. There are two different plenum doors on your vehicle. One opens and closes for heat to the front passenger area. The other one opens and closes for the rear passenger area. There's another answer out there for this rear A/C problem advising owners that the rear control knob on the front dash is bad and replacement is 'a snap'... Can anyone comment on these two trouble-shooting tips?
front wheel drive
There are 2 wiper motors on a Windstar: 1 for the front wipers and 1 for the rear.
depending on if its front or rear, rear 1 hr each front a couple of hours
Most likely the rear expansion tube or valve is defective.
the accuator, located in the rear passenger side is bad. the controls in front when turned go to an accuator in the rear there are two of them one for hot/cold and one for the vents.