A/C problems

I have a 98 ford windstar 3.8
Now the problem is when we have the air on it will blow from the front vents like normal. And then it will switch to the defrost vents up by the windsheild and blow. what in the heck is going on with it. I already changed the fan/blower resistor that was the first problem that i had. fix that and now this. anyway if anyone could lend me a hand on this one it would be much appreciated. ( And thanks for taking time to read this thread.):confused:

I'm not sure if I fully understand the symptoms you've described, but I think you're saying that the air flow redirects from the dash vents to the defroster vents while the control is set to A/C or Max A/C.

If that's so, then I'd suggest that you look at the vacuum control lines and/or the vacuum motor that controls the damper for the defrost. In the past I had a problem with my rear air conditioner where it would blow hot air even when it should have been blowing A/C. This was caused by a bad vacuum control valve in the dash board knob. I realize you're not dealing with the exact same problem, but the cause of your problem could be similar to what I experienced.

I too was confused as to what the exact problem fastasshell was having. I came to the same conclusion that the front air only blows out the defrost path even when they set the control to blow out the vent. It indeeds sounds like the vacuum operated damper mechanism. The fail-safe mode for this assembly is defrost so that you can clear your windows if the mechanism fails to direct the air to the right outlet (defrost/vent/floor/combo of the above). There would be vacuum lines to check, switch mode electrical wiring to check and mechanical damper operations also.

Thanks Guys And Sorry i should have explained the problem i had with a little more detail. But i will try that and let you know if thats the problem.:runaround:

i had this same issue with my 98. There is a small check valve on the vaccum line there was a small crack in the outlet side, and it would slowly bleed out, especially under engine load. It's located on the passenger side near the strut tower i believe. that was my issue. Good luck with yours.

Found the problem it was a hose that had rubed through. the red hose next to the check valve.I didn't have any hose like that around and the parts store said to check @ napa so the best thing i could do was to slide some heatshrink close to the size of the line and shrink it down on to it. I think it will be ok for now So i Thank anyone that had feedback on this thread. (Thanks alot)

good for you, it's always good when the forum comes thru, small problems make big headaches.

Ok hold on a sec i thought i fix the problem but only for a minute or so it blew threw the front vents and then back to the defrost it went. anyway sorry for that false alarm. SO lets start fresh what dose the check valve look like I say this only because on the one thread (brinkz) said something about its over by the strut tower. now i was more like under the cow by the firewall its a black box with a splitter coming off of it a red hose and black hose. now the little thing that connects the back hose and the red hose is that the check valve? does anyone have a pic of one.

yeah sorry you are in the right location...if i recall it was red and it splits as you describe. The issue with mine wasnt apparent till i pulled it off, the line was cracked right where it attaches to the check valve. sorry i dont have a pic...

New problem now check engine light came on so i went to the part store and they said that the code read o2 sensor but then he said may not be your problem sometimes codes are off but what ever it is its messing with the emissions. so now im looking at the iac valve for the check engine light that came on.

The problems might be related. It's a bit of a long shot, but worth considering.

O2 sensors actually measure the difference between the oxygen concentration in the ambient air (sampled in the body of the sensor) and the air in the exhaust pipe. The greater the difference (i.e. the less oxygen in the exhaust) the greater the voltage output. When there is no difference the voltage output is zero.

If you have a large enough vacuum leak, the O2 sensor voltage readings will consistently be closer to zero than expected ON BOTH SENSORS. However, I would think that you'd also have some other engine problems such as misfires when running at idle.

The van idles fine i sprayed carb cleaner around the upper manifold area and by the vacuum lines and no change in idle up or down. the newest thing so far is that i removed the EGR valve a friend at auto zone said that if i clean it i might get a little more life out of it. i dont know this thing is like a kick in the head.

This is what i did today took a look under dash to see if anything was leaking air the only thing i could hear air coming from was the other vacuum control valve the one by the gas peddle with the yellow vacuum line on it. the one i changed before had the red vacuum line on it.anyway when i took it off i could not compress it like the other one so we will see what happens. i hope this fix one or all of the problems that i was having.

Now the AC comes out from the front vents but when going up a hill it switches to the defrost vents.

Now the AC comes out from the front vents but when going up a hill it switches to the defrost vents.


definitely seems to be a vacuum related issue because going uphill would mean more throttle and thus lower manifold vacuum pressure. once you lose the pressure, the hvac controls change to the "failsafe" mode of defrost. probably a small leak somewhere.