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Ford Windstar ac circuit diagram

richard100 on Sun August 08, 2004 10:29 AM User is offline

Year: 1995
Make: Ford
Model: Windstar
Engine Size: 3.8
Refrigerant Type: R134-a
Country of Origin: United States

I have a problem with the a/c on my Windstar:

With the a/c on, the magnetic clutch on the compressor does not engage. I have tested the clutch with a separate jumper wire, and it all works fine. Also, with the connector on the compressor disconnected12V is present at the connector, as expected.

My Chiltern manual does not disclose anything on the a/c: most unhelpful! not even a circuit diagram!. I assume that there is at least a relay controlling the a/c, although it does not seem to be anywhere near the rest of the other relays (ie I cannot hear it click there!)

It all points to a high resistance contact somewhere between the a/c control switch on the dashboard and the compressor itself. THe question is, what is between these two?, and where is it all located, and where might I get a circuit diagram?

Thanks

Chick on Sun August 08, 2004 10:48 AM User is offlineView users profile

Try this first. There is a two wire switch on or near the accumulator (black can). Take the connector off and jump the switch. If the compressor comes and blows cold, change that switch (cycling switch) if it comes on and blows warm, get the pressures checked..Hope this helps...Let us know what you find...

-------------------------
Chick
Email: Chick

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Freedoms just another word for nothing left to lose

richard100 on Sun August 08, 2004 11:59 AM User is offline

Thanks

I tried shorting the cycling switch. still no cold air, & I can still see the compressor not rotating. I measured 12V across the cycling switch connector (when disconnected) and a switch resistance of 1.4ohm

Also:
I pulled the AC control switch on the dash, and get 12V on the purple wire when the switch is pointing to AC. This is a small wire & obviously not powering the chutch directly!

I checked again that there was 12V at the connector to the compressor, but can see that the mag clutch is not engaged or turning the compressor itself

If I directly apply 12V to the compressor, I see the chutch engage and get good cold air.

thanks
Richard

Chick on Sun August 08, 2004 12:06 PM User is offlineView users profile

I don't have access to wiring diagrams for that vehicle (sunday..) but I believe the computer sends the ground to the compressor (not 100% sure) There is a compressor relay in the relay box that does this The realys should be marked under the lid..Find the relay and switch it with a simular one in the box..But one point..When you apply the 12v to get the compressor to run, is the AC cold?? If not, the safety switchs are working preventing the system to run with low charge...Check to make sure it's blowing cold when jumped, or changing relays will not help..Again, I am not sure if this car uses the CCRM or not, perhaps Rob (Ford tech) will be able to answer that question when he sees your post........Hope this helps,..

-------------------------
Chick
Email: Chick

---------------------------------------------

Freedoms just another word for nothing left to lose

Anonymous on Sun August 08, 2004 1:05 PM User is offline


___________________________________________________________________________

I checked again that there was 12V at the connector to the compressor, but can see that the mag clutch is not engaged or turning the compressor itself

If I directly apply 12V to the compressor, I see the chutch engage and get good cold air.
_____________________________________________________________________________

Once had a similar situation. Finally discovered that the relay was making sufficient contact to show 12V on a voltmeter, but would not conduct enough current to activate the device it was controlling. By all means, try Chick's suggestion to substitute a similar relay.

Hope this helps.

Ted

richard100 on Sun August 08, 2004 1:05 PM User is offline

Hi
Thanks for all that....yes the a/c does run cool when I run the compressor directly. I also had the pressures checked a few weeks back.

I found reference to a AC clutch relay....in with the maxi fuses.....but the Chiltern picture and lables do not match the layout in this particular vehicle (1995 3.8 Winstar), and I cannot find one that seems to operate when the a/c should cut in and out.....I swapped them around just in case. but no joy

I think I am going to hit the Ford Dealer to get a cct diagram...I an a bit blind without!

thanks

Richard

robtemple on Sun August 08, 2004 1:46 PM User is offlineView users profile

Many tech's have been fooled by the cycling switch. You have to turn off the ignition, then connect jumper wire, then start the engine and wait several seconds. If comp still wont engage, chances are
it's not related to cycling switch. Other possibilities are IRCM (CCRM/ relay control module which houses the a/c relay), high pressure cut switch.

-------------------------
Rob Temple
Ford/Acura/Hyundai Tech

Anonymous on Sun August 08, 2004 2:22 PM User is offline

I dont know about the Windstar but on my Taurus the ccompressor is controlled by a power transistor in the CCRM. The CCRM contains four relays (high fan, low fan, power to the computer, and fuel pump relay). The transistor is mounted on a heat sink to the side, inside the metal case.

friendplus on Sun August 08, 2004 4:29 PM User is offline

test voltage in the connector of the compressor, using a pilot,bulb of 10 watts, not a multimeter, each terminal with the positive and negative and you found if positive or negative is no present in the connector when turn on the switch of the a/c.

richard100 on Sun August 08, 2004 10:03 PM User is offline

Thanks to everybody for for all the replies....it seems as though Rob has nailed it...It seems to be the cycling switch.....you are right, you have to wait almost 30sec for it to engage after jumping the switch (it appears that you do not have to turn off the ignition though). I would have never got that one...I was expecting it to cut in right away on jumping the switch!
So, I will get a new switch tomorrow and see what happens....

thanks

Richard

richard100 on Mon August 09, 2004 10:21 PM User is offline

New switch sorted the problem...thanks to all

Richard

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