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Which wire is right wire?

Caprock Rider

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West Texas
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2002 (3 trucks)
Make / Model
Ford Ranger XLT
Engine Type
3.0 V6
Engine Size
All three 3.0's
Transmission
Manual
2WD / 4WD
2WD
Tire Size
all 15", from 225/70 to 31x10.50
My credo
To each their own ____. If it's no skin off my butt, then I couldn't care less.
Dropped by a local Ford house yesterday to get an electrical schematic of the A/C system. Although I did get one, it is just an overview schematic showing what devices are connected to what.
My go-to person for these schematics told me that is the best he could do because Ford has removed the more detailed schematics for 2002 Rangers from their system.

So today I did some checking with my meter, then some trial & error tinkering in an effort to determine where to splice in a toggle switch that would override the A/C controls.
My goal is to prevent the A/C from operating when I'm using the heater and/or defroster.

The heater/AC selector switch has 4 wires plugged into the back. Of course, one of those wires (black wire with 2 green stripes) comes from position F2.2 in the CJB with 12 volts. Discovered today
disconnecting the top wire (gray wire with 2 yellow stripes) on the back of the switch still allows the heater and defroster to function, but the A/C clutch never activates. This is what I'm wanting.

However, before I cut this wire and splice in a toggle switch, I was hoping one of the sharp minds in this group could either confirm I have
the correct wire to accomplish my objective, or tell me why I'm barking up the wrong tree.
 


franklin2

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You can see from the diagram, most of the compressor wiring is under the hood coming from the underhood fuse box.
 

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franklin2

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I think I see your grey/yellow wire in this picture. It looks like this is the wire that tells the PCM when to turn the compressor on, since the compressor is somewhat controlled by the PCM. Looks like you may be on the right track with your wire you found.
 

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RonD

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Don't over think it

Compressor has 2 wires, 12v and a ground, it can't come on with either disconnected
Cut the ground wire and run same gauge wire into the cab, just the 1 wire
Hook that wire to your switch in the cab and then ground the switch's other terminal in the cab, you can even use a lighted switch, so it comes on when compressor is grounded(switch on) and compressor cycles on(has 12v from relay)

If you want to keep all wiring in the cab then pull out the climate control panel and cut the Purple(violet) 12volt wire that comes out of the MODE switch, that wire tells computer to activate AC when it has 12volts
Hook up switch between the two ends of cut wire, it gets 12v from fuse 10 in cab fuse box, 7.5amp, just in case you need to replace it if you cause a short :)


Just as a heads up, the AC system Dries the air in the cab, so makes Defrost work better and keeps musty smells away in winter when you get into the cab with wet cloths/shoes
This is why it comes on in other Modes besides AC
 

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Caprock Rider

New Member
Joined
Nov 16, 2015
Messages
22
Reaction score
11
Points
3
Location
West Texas
Vehicle Year
2002 (3 trucks)
Make / Model
Ford Ranger XLT
Engine Type
3.0 V6
Engine Size
All three 3.0's
Transmission
Manual
2WD / 4WD
2WD
Tire Size
all 15", from 225/70 to 31x10.50
My credo
To each their own ____. If it's no skin off my butt, then I couldn't care less.
Thank you franklin2 and RonD for your expertise and the pdf's.
Forgot to mention in my post that I wanted to stay inside the cab if possible.

After studying the schematics I feel I was on the right track with the gray/yellow wire. That wire brings the 12 volts to the mode switch so the purple wire
can take it from the switch to the PCM. However, I'm going to follow your advice Ron and splice into the purple wire. On that side of the switch,
the purple wire wouldn't necessarily be hot all the time. Whereas the gray/yellow wire would be hot all the time.

FYI my reasoning behind this modification is to save my compressors. Allow me to explain this way. All 3 of my Rangers are fairly high milage. In addition
to that our summers here in West Texas are long & hot. 100º+ temperatures are over for this year, although most days are still in the 90's. 94º today.
Thus the A/C compressors really get a workout.
Don't feel I need to wear out my compressor drying air that is already less than 30% humidity most of the time. It is not uncommon for the humidity level
to be in the single digits. I have seen 5% humidity. I have seen 7% humidity more times than I can remember. Yes, we do get rain. Around 16" every year.
This year will probably be less, maybe 13 or 14" of rain total.
Thanks again fellows.
 

RonD

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Well there is wear on some things from use, most things in fact, but.......................
Tires and brakes are a perfect example of use wear, most would agree that these wear out based on use, miles driven

The but is because there are things that wear out FASTER from disuse
People with seasonal use engines will know about this, lol
Unless you start the engine and run it for 5 minutes or so once a month, you WILL BE having to service/repair it when you need it after sitting for 6 months plus, lol
Plus its hard on engines to do Dry Starts, i.e. oil has drained out of all passages after a few months, but thankfully engines that have been sitting for 6 months usually won't start up right away because of fuel issues, lol, so trying to start them circulates the oil before start up :)

The compressor has oil in the fluid it circulates, this lubricates the internal bearings when compressor is running
So being OFF for 6 months at a time will cause dry starts in the compressor, so I would activate the compressor once a month and use it for a day


And as for tire and brakes, anyone who has stored low mile collector type vehicles knows the pain of having to replace almost new tires that are now 10+ years old and are cracking, or bringing vehicle out on a nice weekend and having a brake freeze up from disuse
Not to mention having to replace the battery every few years, lol, even if it was disconnected

Some things can last longer if used as intended
 

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