Rear heat on 99 - floor only?

I bought my 99 SEL used. The rear heat has always blown out of the vents on the roof as well as the large vent on the floor. This summer we had some AC work done and now the rear heat only blows out of the large vent on the floor. I did a google and found a used car review where the reviewer mentioned the same thing only made it sound like it is by design. Can anyone please verify if the rear heat only blows out the floor vent?

Thanks...by the way, all my p 171 and 174 problems are long gone thanks to the knowledge all of you share on this board!

It's quite possible someone "fixed" something you didn't want "fixed".

By design, (beginning in '99) there is a rear "mode" door and a rear "blend" door. The blend door mixes cool air with warm air to give you your selected temperature.

Depending on the setting of the temperature, the mode door also finds a position ... of directing air flow to the ceiling or the floor vents. I think I remember that a more warm setting goes downward, a more cool setting goes upward. Some folks (me included) find this situation a little anal and do something to correct the "problem". The prior owner probably removed the lower left rear quarter panel trim cover and disconnected the electrical connector feeding the mode door. Perhaps he even blocked the mode door in a particular position.

Your repairman probably thought he found a connector "unintentionally" loose and reconnected it. ... and removed the "block", if there was one.

interesting. I can't imagine why I or anyone else would only want the heat on the floor (and only on the driver side I believe). Doesn't seem like it would work well. Does anyone have a wiring diagram I could use to disconnect the connector to the mode door?

interesting. I can't imagine why I or anyone else would only want the heat on the floor (and only on the driver side I believe). Doesn't seem like it would work well. Does anyone have a wiring diagram I could use to disconnect the connector to the mode door?
I have a 2001 and my heat blows out the bottom side it gets hot in there. and AC blows from the top. Only problem with mine my rear control does not work. I traced it to the switch I think. But I like being in control and left it be.. lol

I have a 2001 and my heat blows out the bottom side it gets hot in there. and AC blows from the top. Only problem with mine my rear control does not work. I traced it to the switch I think. But I like being in control and left it be.. lol

Hello,

Heat rises this is why the heat is on the floor. Cold air falls. This is why the a/c is from the ceiling. This is the way that the system is suppose to work. You should thank the person that FIXED your van.

Nice Day

WindstarSufferer,

I believe the climate control designers were full (fool) of very good intentions. It's hard for me to believe that they actually "field tested" this design and yet did not discover the errors. (You forget all that "hot air rises" theory because the air is forced by a fan.)

On other more costly trucks, such as the Excursion, the blend door and the mode door are controlled separately by individual controllers. But that probably costs Ford an additional dollar per unit.

You don't need a wiring diagram to find the connector. Once you remove that trim panel, its pretty obvious.

Actually, if I recall correctly the scientific theory is that cold air is more dense and FALLS, thereby displacing the warm air which has no where to go but up. In which case, putting a fan on the floor causes the cold air down there to get mixed up with the hot air from the heater causing a blend. Very smart indeed.

You see a bunch of designs lately in houses which place the vents up top because it provides a nicer blend, one that you don't feel, no drafts and no hot spots. But this is a car and the darn overhead vents blow right on top of you and in my opinion you'd cook your head in two seconds with full heat overhead. In the summer that overhead AC is real nice as it cools the heat radiating from your head. I think the stock design is a better comfort thing.

I wouldn't go disconnecting that thing by default though. Unless you've had 4 classes in thermo(dynamics|statics) / physiology. Can't really see a reason for bypassing it other than an experiment.

Be forewarned that it will probably trigger an DTC with the Rear Electronic Module. It won't turn the MIL light on but it will be there. Maybe that's what your HVAC mechanic discovered when servicing the system. But hard to believe that the guy would have gone through the procedure of removing the rear seats and panel trim just to connect an electrical connector when most AC work is done under the hood. Maybe a relay was out? I can't explain why it would be different than before. Best to take a look at your itemized bill and see how much time they charged you and for what. The rest of us would just be guessing.

I'll leave it be for now. I can say that having had the heat come from above last year was VERY nice. It felt much nicer than it does now. What makes NO sense to me is only having the rear blower on one side of the van. It's basically blocked by a captains chair so one side of the van won't get heat unless I crank the heat on high (and then it is really noisy).

Anyway, thanks for answering my question. I was at least able to assure my wife that she doesn't need to get anything fixed. After all, like the rest of you, I've certainly spent my fair share keeping the Windstar up and running...

Now if I could only figure out the ABS / traction control problems....

(WindstarSufferer ....shssss ....
Don't complain about the one-sided rear vent system. There are some true-believers here who will explain, using a fluid mechanics treatise, how this blast of air helps offset the roll of the car when accelerating ... keeping the left rear passenger vertical in his seat. Be grateful!)

Please forgive an old man (who passed all his thermo courses many years ago ... and has long since forgottened every thing once learned) for being foolish.

Not that I want to drag this thread on any longer....and I have no idea how fluid dynamics got involved here....but my curiosity has me asking the question, "did you want the heat from both sides of the rear doors instead of one?"

I thought the reason for having the heat from the driver's side was obvious....because that's where the heater core is. There is a heck of a lot of pressure coming from that corner. Not sure I could imagine how you would push that air under the van (through a large insulated chamber) and back up the other side without putting in a small aircraft propeller.

Either way, I like the system (other than the seat belt obstruction), I'm happy I have rear air controls for those in the car who are going through menopause, and if I could find any car manufacturer who actually has the climate system right I'd be surprised.

HVAC is a funny topic for me because there is so much done wrong. Houses in particular. Anyone who hires a plumber to install their HVAC might as well have a chiropractor perform their open heart surgery as well :)

Fluid Dynamics: The branch of science that is concerned with the movement of gases and liquids. -American Heritage Dictionary.

I agree with you, many auto manfgr's get climate control screwed up ... but if you're looking for the worst, look no further than Ford. I think a chiropractor; posing as a plumber, suffering from menopause and restrained by a seat belt; could design a better climate system. LOL.