A/C issues - Tracking down Wire Diagrams and seeking ideas - Taurus Car Club of America : Ford Taurus Forum
 
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post #1 of 9 (permalink) Old 03-26-2019, 11:06 PM Thread Starter
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A/C issues - Tracking down Wire Diagrams and seeking ideas

First technical post here on TCCA but I'm no stranger to webforums and working on cars.

I have a 04 Wagon with the v6 - OHV engine and my A/C works, but it is on all the time, even with the switch in the off position. The clucth does in fact work as it disengages when i remove the fuse of which I currently have out. I would also note that disconnecting the pressure switches does NOT disengage the clutch. I got the car from a relative and it was in an accidnet and put back together with parts from a 01 Sedan. I am thinking a ground or something was missed. I would also note there was one broke wire going into the fure box that my relative decided needed to go to ground in stead of hte other end of the broke wire. I hooked it back up correctly, but now the A/C does not kick on with the fuses back in unless I gorund this wire out.

I have found some mentions of Oxygen sensors and other grounds could be a clulprit but not sure yet. If anyone has some FSM printouts or other ideas I am all ears as summer is coming up fast. I will gladly answer any questions and post pictures later once I get my post count up.

Thoughts:

ground issue somewhere
dash knob/switch issue
broke wire somewhere
ECM issue (not knowing the AC knob is on)

Thanks for any and all feedback!
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post #2 of 9 (permalink) Old 03-27-2019, 08:56 PM
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Kind of basic but have you swapped out the relay?

It's SHO time!


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post #3 of 9 (permalink) Old 03-28-2019, 09:03 AM
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well, mixing different years parts on a taurus can be a recipe for fun.
Long ago and far away, i put a 96 motor in my 97. started, drove,
seemed OK. but could not code scan and AC didn't work.
The dude that dropped my motor in did NOT change the engine wire
harness and left the 96 engine harness on the motor.
It should be the same, right? all the connectors looked the same.



after untold hours of research and 96 and 97 electrical
schematics, i found out ford has a bad habit of changing a few
wires around frequently in there wiring. Maybe not enough
to make the car not run, but enough to cause issues


By the time i discovered this, my old 97 motor was gone
with the proper harness on it. I had to figure out what was
wrong, break open the harness, and rewire 4 wires.


In my case on the AC, the ground for the pump was

wired differently between the 96 and 97 engine harness.


Swappers beware!

Bob Urz 1989 Vulcan wagon (wife crashed) 1990 Vulcan sedan (sold running) 1993 Vulcan sedan (wife crashed) 1993 Vulcan wagon (beat up like Battlestar Galactica, drove to junkyard on a sad day) 1997 Vulcan sedan (down with multiple coolant leaks), 1998 Vulcan sedan (rescued from being junked three time with broken brake lines and bad rack, hydrolocked engine replaced ) down for now
Note: wives and daughters are dangerous to your Taurus health!

If Spock drove a Taurus it would be a Vulcan
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post #4 of 9 (permalink) Old 03-28-2019, 12:32 PM Thread Starter
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I have swapped relays around, fuel pump and horn or both I can't recall and no change
All fuses are good

I did have to remove the relay to get it to stop turning before I found the broke wire and it would always cut it off


Currently I rigged up a rocker switch to the broke wire which feeds the relay and sends that wire to ground. When grounded the ac turns on and when flipped off it turns off like it should. The A/C runs constantly and will freeze up if allowed to in this state. I will run it intermittently for now while driving down the road and turn it off from time to time and when I come to a stop or have reduced air flow.



With this said, it makes me feel like the broke wire from the harness side is not grounding when the selector switch calls for AC. If the selector is not telling the ECM for AC then the fans don't kick on like they should either I think (i'll have to confirm with you lot as I think the fans should kick on regardless of vehicle temp when ac is on). The Selector switch also tells the ECM the AC is on so it can monitor the evap temp and engage the circuit so the high/low pressure switch will kick the system off. It would be nice to know the switch wires to test to verify this.



If anyone has access to an FSM for this 04 I would be appreciate.
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post #5 of 9 (permalink) Old 03-28-2019, 07:51 PM
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well, my question is what was used off of the 01 sedan and swapped into the 04.
that might lead you in the right direction on where to look.
i found my schematics on line, but these days, you do searches and dam
google gives you mostly pay to play sites to download anything.


bob

Bob Urz 1989 Vulcan wagon (wife crashed) 1990 Vulcan sedan (sold running) 1993 Vulcan sedan (wife crashed) 1993 Vulcan wagon (beat up like Battlestar Galactica, drove to junkyard on a sad day) 1997 Vulcan sedan (down with multiple coolant leaks), 1998 Vulcan sedan (rescued from being junked three time with broken brake lines and bad rack, hydrolocked engine replaced ) down for now
Note: wives and daughters are dangerous to your Taurus health!

If Spock drove a Taurus it would be a Vulcan
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post #6 of 9 (permalink) Old 04-10-2019, 11:20 AM Thread Starter
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Right, I am hoping to find some old schooler on here who will pm me a secret link to a FSM


I did get my hands on some from Fords service counter but have not find any issues yet. I may pull the radio/hvac thing and tinker with those wires or use a jumper there to test for continuity.



I am still struggling if the AC is switch controlled or ECM controlled.



Mostly cosmetic stuff like front bumper, headlights, hood, AC evaporator,radiator, some support pieces and power steering pump.
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post #7 of 9 (permalink) Old 04-10-2019, 12:02 PM
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Ok, one answer at a time. The HVAC selector switch sends signals to the PCM. The PCM controls the compressor clutch through the relay. There is a low side pressure switch that cycles the clutch off and on to control high side pressure and evaporator freezing. There are schematics available anywhere you look (Haynes manuals, All-data, Google, etc.) Most people who attempt diy A/C repair usually do more damage or spend more money than necessary.
Now, I have some questions for you:
Do you have a DMM?
Do you have an A/C gauge set?
Do you have a recovery / vacuum pump?
What color is this wire that was grounded?
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post #8 of 9 (permalink) Old 04-10-2019, 12:38 PM
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well, it didn't take long to find something close on google.
this is off a 2000 but it should be similar:


http://taurus-club.ru/manuals/Ford_T...000_wiring.pdf


is yours automatic or manual climate control?


bob

Bob Urz 1989 Vulcan wagon (wife crashed) 1990 Vulcan sedan (sold running) 1993 Vulcan sedan (wife crashed) 1993 Vulcan wagon (beat up like Battlestar Galactica, drove to junkyard on a sad day) 1997 Vulcan sedan (down with multiple coolant leaks), 1998 Vulcan sedan (rescued from being junked three time with broken brake lines and bad rack, hydrolocked engine replaced ) down for now
Note: wives and daughters are dangerous to your Taurus health!

If Spock drove a Taurus it would be a Vulcan
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post #9 of 9 (permalink) Old 04-10-2019, 12:49 PM Thread Starter
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Quote:
Originally Posted by rsteve56 View Post
Ok, one answer at a time. The HVAC selector switch sends signals to the PCM. The PCM controls the compressor clutch through the relay. There is a low side pressure switch that cycles the clutch off and on to control high side pressure and evaporator freezing. There are schematics available anywhere you look (Haynes manuals, All-data, Google, etc.) Most people who attempt diy A/C repair usually do more damage or spend more money than necessary.
Now, I have some questions for you:
Do you have a DMM?
YES

Do you have an A/C gauge set?
YES

Do you have a recovery / vacuum pump?
No Recovery tank but yest to Vacuum Pump
What color is this wire that was grounded?
It is kind of a brown/tan stripe or orangish with tan strip wire. One end goes into the wireloom by the battery and the other goes into the fuse box and connects I believe to either the AC relay or the AC fuse.
And as a side note the AC is working, good pressures on high and low side, I just have to ground that one wire for it to kick on and turn it off and on to keep it from freezing up.



So I am guessing like this:
Selector Switch grounds the PCM to send power or ground to the activate side of relay. Power then goes from the ac fuse to the ac compressor. I am guessing the compressor's neg goes through the pressure switches.



The PCM also tells the fans to kick on (which I am not getting at the moment), and to also monitor the evaporator temp to keep it from freezing up and will cycle the compressor signal that way. I am guess it will also cycle on WOT (wide open throttle) as well.
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