Another air conditioning question

1998 Ford Windstar GL 3.8L

I have the classic issue with the cold Air only blowing in defrost mode and the rear air is only blowing out of the bottom vent and is hot. I need to get this fixed, my wife is due this month with our fourth child and the Pontiac Comp g does not hold that many people :)

I originally found that I had a vacuum leak uner the cowl and that fixed it for a short time. It failed again and I looked for another vacuum leak and could not find one.

My questions are;
*What else can cause this problem and could the front and rear issues be from the same cause? I have read from old posts that the front/rear switch or actuator could be the cause.

*Does anyone have anymore information on these parts and how to test them and also where I could buy them at and part numbers if available (local parts store or dealer item)? I have a vacuum tester but I really do not know how to use it to diagnose these problems.

Any tips or direction would be greatly appreciated!!

OK....my '96 did NOT have the rear heat/AC unit, so I have NO personal experience with that.

The FRONT unit issue that you are having is a lack of vaccum to the actuators that hold the diverter doors in position.
With NO vaccum, they will be in the position to direct all air to the defrost vents (windshield).
If you look up under the dashboard....you will see the door actuator "bulbs" with the vaccum lines running to them.

There is a vaccum "resevior" in the engine compartment.....on the passenger side firewall.
This box holds a vaccum when the engine is not running, to hold the doors in position until you start the engine again.
I would start at that location.....and follow the vaccum lines to see if you can find the location that the vaccum is lost.
It can be lost due to a disconnected vaccum line, or broken or smashed vaccum line.

Do not confuse the diverter doors for airflow with the "blend door" that controlls the mix of hot/cold air to control the air TEMPERATURE.

Ford has in the past, on some models, included a vacuum hose diagram in the same book that described the electrical circuits. On my '99's circuit book, the vacuum diagram was dropped. I don't know if it is included on the '98 or not. Its a great help if you can find one ... perhaps at a Ford service center.

I have installed a manual shut-off valve that allows stopping the flow of hot water to the cabin heater cores. Good for the hot weather.

well I took the dash apart and unplugged the two vacuum lines at the front/rear selector switch then plugged the lines with my thumb to see if anything would change. It switched to the normal dash operation so I norrowed the front issue to the front / rear selector switch is bad. I would assume this would be the issue with most of the vans with the defrost issue.

Does anyone know if that switch is available through the parts store or just the dealer? Now I am trying to figure out the rear operation. Do you think that it may have to do with this same switch? I am replacing the white vacuum line that goes from the rear vacuum arm to under the vehicle. I will keep this post updated.

I just did a quick look at the rockauto website.
I did not find the rear selector switch........but maybe I missed it.
If Rockauto does not list it.....then you most likely need to get it through a dealership.

Until you get the new part.....you should be able to plug the vaccum line to the rear unit select switch and regain control of the front unit.

I did plug the vacuum lines at the switch and have full control of the front. In the process of looking around the rear ac line cracked and leaked all of the freon....Figures!! Is there away to eliminate the rear air and still have the front work????

For now I just used a rubber line with two clamps on each side and RTV at the ends to seal it. I am afraid to spend the $70 to recharge the unit and not have the fix hold, and with my luck the other line will or is cracked. I would really like to eliminate the rear air if possible.


edit: I found the switch online, I still want to eliminate the rear ac if possible though. http://www.autopartswarehouse.com/details/QQFordQQWindstarQQMotorcraftQQBlower_Control_Switc hQQ19951998QQMIYH1465.html

anyone know if I could cap off the rear lines and still have the front work? I am not sure if it has to be a loop type flow or not.

You would want to cap off each line separately ... no loop. The front unit will continue to work without the rear, as long as there is no loop for refrigerant to flow through.

good... thanks I will try and find some caps that fit and then braze them in there.

I would try to find somewhere in the engine box to do the capping.

Good idea, it will cut down on the amount of freon I use. the thing takes 3.5 lbs or so

Not sure about R134a, but R12 could generate some serious poison when exposed to a flame. Best be careful.

all of the freon leaked out when the line cracked while looking for the vacuum issue. made a pretty big fog and smelled bad, It is not as bad as R-12 though.

It looks like the proper way to eliminate the rear AC in your van would require replacing the accumulator and the discharge line assembly on your van with a standard AC setup. Granted its not the cheapest option, but its the most future trouble free.