A/C flow goes to defrost

luarca · 05-09-2010, 02:35 PM

Hi, I have a 97 Ford Aerostar and recently i am noticing that when I am going uphill or at more than 60 miles the air conditioning start blowing at the defrost vents and the rear unit starts blowing out off the floor vents. A friend told me that it might be a vacuum leak and start moving some tiny hoses and now it is worse, anybody that can share a diagram on how to put all this hoses back? or an idea of what is going on?

electro · 05-09-2010, 03:20 PM

You defiantly have a vacuum leak.
If you examine the hoses you mentioned, you may very well see the leak. If your lucky, you may also hear the leak. Do you have good vacuum at the reservoir? The problem could be on either side of the firewall.

Poppy · 05-09-2010, 08:14 PM

I fully agree... vacuum leak.
This might be helpful in checking under the hood for vacuum leaks.
Pictures of 1998 windstar vacuum lines

I thought that I put something together for under the dash, I'll see if I can find it.

Poppy · 05-09-2010, 08:15 PM

Ah... here it is

This should help a lot.
windstar rear AC problems

Skyhawk · 05-11-2010, 06:29 AM

You may also have a vacuum motor with an internal vacuum leak, commonly a leak in the diaphram, such as the blend air door motor.

Poppy · 05-11-2010, 10:44 AM

A way to test a vacuum motor/actuator is to pull a vacuum on it and see if it moves, or to depress it and plug the vacuum line to it with your finger ans see if it stays depressed. IF it doesn't it is leaking internally and need to be replaced.

tempodoc · 09-05-2010, 05:51 PM

I am having a similar problem on my '92 Tempo GL. I pressed defrost today and the control switched to defrost but will not switch back to anything else. I have done some research that points to a vacuum hose (on other ford models) on the firewall that may need to be checked. I guess that the module that the hose connects to is inside of the car? I bought a Chilton's manual on E-Bay for $6 and will fix the hose as soon as the manual comes in.

If anyone would like to reply and clue me in as to where the hoses are I could fix this a bit sooner. A diagram or picture would be extremely helpful. Its summer in Florida and I suppose a cool defrost is better than nothing.

tempodoc · 09-06-2010, 10:00 AM

Fixed it!

"Under the hood at the center of the firewall, there is a thin rigid black vacuum line connected into either the vacuum manifold or into another rigid tube... the other side goes into the firewall. From there it goes behind the dash, ... then it plugs into a veresser right behind the glove box (if you pop out the glove box door, you will see it, its right next to the seat-belt control module) from there the vacuum supply hose is WHITE...."

The white hose is connected to a module to which a very thin black hose / tube (the main) is also connected.
I traced the black hose to and through the firewall to the engine compartment and found the "hose" poking out of a hole in the firewall that was in a space of bare (unpainted) metal. I traced the hose along its length (approx. 1 foot) to a break at the base of the small rubber boot that connects to a point along a black plastic PVC tube that extends vertically. I removed the boot and used a small alan wrench to gently force the broken end out of the boot. I then inserted the end from the firewall into the boot and bingo the A/C control works perfectly!

I would recommend using some super-glue to glue part of the tube to the boot but the pressure is not so high that it is mandatory.

Poppy · 09-06-2010, 06:32 PM

Thanks for posting back, I'm glad that you figured it out.