Radiator Fan Always On

[arteliare]

I have a 2000 Windstar 143K Kms (around 90K Miles) the radiator fans (both) are always on, I changed the the water sensor but has not helped. I took it to the dealership and they could not fix it.

What could that be?

[12Ounce]

On the '99, and I expect on the '00, there are two dedicated relays for the radiator fan. They are the only two relays mounted on a separate mount very close to the left hand shock tower on the inner wheelhouse. I suspect one of these relays has its contacts stuck together. Just in front of the windschield cowling.

You should be able to determine which by pulling them one at a time.

[LeSabre97mint]

11.9ounce (just trying to be funny)

One would think if it was "only" a relay that the dealership could figure that one out! One would hope that the parts changer (mechanic) would have gone down that path!

Dan

[12Ounce]

But how can we have any faith in a "dealership" who couldn't find this one ... whatever it is!

(After the holidays, I'm "Several thousand Ounces".)

[arteliare]

Thank you 12Ounce, your comment made sense....I checked the relay and hit it to see if that would help....and the thing started to turn on and off as it should....I will buy another relay....on the comment related to the "stealership" (not dealership), I do not have any faith in them....they connected the vehicle to the computer and could not find anything....they did not use common sense as 12Ounce did it....

[tripletdaddy]

Good or bad, computers don't have common sense yet. Which would be harder, for everyone to have common sense or to program computers to have common sense? As it is, we are already obsolete without computers possessing common sense, because we all don't have it or don't know how to use it. But, once computers posess it, we will be so useless, we will only be good for serving the computers!?!

[LeSabre97mint]

Originally Posted by LeSabre97mint

EDIT 119.ounce (just trying to be funny)

One would think if it was "only" a relay that the dealership could figure that one out! One would hope that the parts changer (mechanic) would have gone down that path!

Dan

You noticed that I said the parts changer (mechanic). Come on man...think...!!!

What do you pay Ford to tell you that they don't know how to think any more?

Dan

[philkb]

Originally Posted by LeSabre97mint

You noticed that I said the parts changer (mechanic). Come on man...think...!!!

What do you pay Ford to tell you that they don't know how to think any more?

Dan

Although dealerships (should) only employ certified mechanics, it is amazing how many have very poor electrical knowledge or even experience. That may be the situation here. Still it's hard to believe a dealership would just give up like that.

Phil

[bdahl385]

I had this problem on my2000 Windstar for over 4 years before getting it diagnosed and fixed last year. Cooling fans would cycle on/off properly if I unhooked the battery for a few minutes to reset the PCM. Fans would cycle fine until I turned on the A/C one time. From that point on, both fans would run constantly even with a cold engine and the A/C off. Unhooking the battery cable would temporarily fix things until the A/C was turned back on.

Did a google search and found a Ford technical bulletin about a high pressure Air Conditioner sensor that fails and causes the fans to run in high speed "fail safe" mode. The sensor, can't remember the part number, was located directly under the cooling fans and radiator on an A/C line.

I couldn't find the link anymore to provide the exact article. Hopefully one of the great forum experts will pick up on this solution and give you more complete info to see if this is your cure.

[discnik]

bdahl385, Are you talking about the cooling fan dropping resistor ?

[philkb]

Originally Posted by discnik

bdahl385, Are you talking about the cooling fan dropping
resistor ?

He is referring to a sensor which operates when the AC refrigerant pressure is too high, and will turn on the fans at full speed in an effort to bring down the pressure. This could happen in very hot weather or an overcharged AC system. You can see that if that sensor went bad, it could cause the fans to continue to run high, even when all is OK. Unplugging the sensor when the fans are stuck on should prove it out. That is assuming that the switch CLOSES when overpressure is present and goes open normally.

Phil

[bdahl385]

Correct PhilKB - it's a sensor in the high side A/C line that was faulty and caused my fans to run high speed constantly. I found the webpage (a PDF) file that originally led me to the symptom and cure. Look at paragraph 2 on page 2 under "Ford Quick Tips":

http://www.carquest.com/common/downl...ps_Fall_05.pdf

The sensor itself is located right below the oil dipstick. There is an A/C line with a larger golf ball sized canister where the sensor and wiring harness are located.

[discnik]

bdahl385 Thanks for the thread.

[tripletdaddy]

The high pressure cutoff switch does several things. It's actually two electrical switches in one. Normally, at lower pressures, a switch remains open indicating to the PCM to only run the fans at low speed. The switch won't close until the pressure reaches approximately 325 psi, at which point the PCM is signaled to put the fans at highs speed as Phil indicated. The fans will stay at high speed until the pressure drops below around 250 psi, at which point they will return to low speed. I would differ with Phil in that the fans go to high speed not because the pressure is too high, but there is such a large heat load on the ac system, like when you start up the ac on a 90 deg day in the sun. When the pressure is in fact too high, around 425 psi, the second switch in the sensor will open the ac coil power circuit, stopping the compressor from running - kind of like a snowball going down a hill. If you don't stop it, it will only go higher and higher. In addition, in case the switch fails, there is a relief valve on the compressor or on the high side line between the compressor and the condensor. JFYI

Anyway, in bdahl385's case, the switch was stuck closed, telling the PCM to run the fans on high all the time.

[bdahl385]

4 years later, my "Fan Always On" problem returned. I had used an engine de-greaser and garden hose water to clean up a grimy sludge/road grit area right below the EGR valve. The next day i noticed both fans were running at high speed right after cold engine start. I went to the sensor, pulled off the connector and found water had gotten inside. Sprayed out with sensor safe cleaner and let dry. Problem went away. One week later i get drive thru automatic car wash. Within hours I hear the high pitch sound of both fans running high speed again. Once again water is found inside the sensor after i remove the plug. Now I know i have a "sealing issue" as water should not channel down into the connector.

Unfortunately, this time cleaning the connector did not solve problem. Luckily I had saved my failed sensor from prior incident so swapped the two out to see what happened. Every thing worked normal for 1 week and then a/c compressor would not stay engaged. As soon as I turned on a/c, the compressor would engage and drop out.

I put back on the other sensor, now a/c compressor working fine but fans run all the time. I ordered new switch from RockAuto, 70 bucks with shipping. Installed and now everything works fine again. I also used silicone RTV to fully seal the top end of the sensor harness so no more water can channel in.

Bottom line is that the sensor monitors two events. Upon sensing high a/c pressure, it sends signal to fully engage both fans at high speed. The second event it monitors is whether pressure seems normal so as to allow a/c compressor to stay engaged. Of my two failed sensors, each had the different function fail.

Other note is that the sensor can be removed and replaced w/o losing refrigerant. There is a Schraeder valve that it attaches to so you just get a very quick puff of gas when replacing.

Here is a link to a very good webpage that shows more info on this sensor as well as how it is easily diagnosed with the proper scan tool and operator knowledge. It also details the problems it caused for the electrical system:

http://www.sparkys-answers.com/2010/...-burnt-up.html