AC Relay Help-any help GREATLY appreciated

CoupeRon

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Sep 10, 2011
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Hello all...new to the boards and have already learned a ton! Hoping someone can help me out. I just bought a 93 Mustang LX Coupe that the previous owner installed a crate motor 306 in. Before doing so, he took everything out of the engine compartment, sand blasted it...etc...the right way. All AC was said to be working at the time everything was pulled. When I turn on the air, the blower motor comes on, but the AC clutch does not engage. I replaced the clutch cycling switch and toped off the R134 so the pressure is good (around 55 at 90 degrees) . I can get the ac to run cold when I jumper wire the positive side of the compressor. I then figured it was the AC relay. I purchased on from Pepboys...but cannot locate the relay ANYWHERE. There are no wires in the passenger fender anywhere (I even pulled the fender well back. I cant find it on the drivers side, or under the dash or behind the kick pannels anywhere. I did notice that there are 3 unconnected/unused connectors coming off the harness by the condensor. Could it be that there is a missing harness that plugs into one or all of these? ANY help at all...including PHOTOS would be greatly appreciated!!! Thanks again to all for the warm welcome to the boards. Ron
 
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dgollem

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May 5, 2004
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Is the low pressure switch connected. It is on top of the drier on the fire wall, passenger side. Search AC r 12 -r134 conversions here and you should find a picture
 

Mustang5L5

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Jump the low pressure switch on the accumulator bottle and see of that turns it on. If it does, double check your pressures and then replace it.
 

CoupeRon

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Sep 10, 2011
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Thanks for the responses so far all. I replaced the relay/switch on top of the black canister on the firewall and it did not help. I was calling that the clutch cycling switch and the condenser...is that the drier guys?? Also...where do I find the low pressure switch? I checked all the fuses...they are good. It just seems wierd that there is no relay on the passenger fender like most people talk about here on the boards.
 

CoupeRon

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Sep 10, 2011
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Mike...I just looked again...it is completely missing and there are no loose wires there either with the exception of two white, tubular connectors (one coming from the same harness as the Mass air wires...????/ Ugh. Do you have any photos that show the relay and where the wires come from??? thanks again for the help...this is driving me crazy. Ron
 

jrichker

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92-93 5.0 Mustang A/C wiring


Diagram courtesy of Tmoss & Stang&2birds


See the following website for some help from Tmoss (diagram designer) & Stang&2Birds (website host) for help on 88-95 wiring Mustang FAQ - Wiring & Engine Info Everyone should bookmark this site.

Ignition switch wiring
http://www.veryuseful.com/mustang/tech/engine/images/IgnitionSwitchWiring.gif

Fuel, alternator, A/C and ignition wiring
http://www.veryuseful.com/mustang/tech/engine/images/fuel-alt-links-ign-ac.gif

Complete computer, actuator & sensor wiring diagram for 88-91 Mass Air Mustangs
http://www.veryuseful.com/mustang/tech/engine/images/88-91_5.0_EEC_Wiring_Diagram.gif

Complete computer, actuator & sensor wiring diagram for 91-93 Mass Air Mustangs
http://www.veryuseful.com/mustang/tech/engine/images/91-93_5.0_EEC_Wiring_Diagram.gif

Vacuum diagram 89-93 Mustangs
http://www.veryuseful.com/mustang/tech/engine/images/mustangFoxFordVacuumDiagram.jpg

HVAC vacuum diagram
http://www.veryuseful.com/mustang/tech/engine/images/Mustang_AC_heat_vacuum_controls.gif

TFI module differences & pinout
http://www.veryuseful.com/mustang/tech/engine/images/TFI_5.0_comparison.gif

Fuse box layout
http://www.veryuseful.com/mustang/tech/engine/images/MustangFuseBox.gif
 

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CoupeRon

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Sep 10, 2011
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Thanks for all the help so far guys....I really need to see how the wires run from the relay on the strut tower and where they go to. I am hoping I don't have to recreate everything....I am hoping some of the un used/unattached connectors laying around on the pass side are some how just missing a harness to pluc into. Does anyone have a photo or photos of the relay in place and how the wires connect to them???? THANKS AGAIN!!!
 

Mustang5L5

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Feb 18, 2001
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Trying to find a pic...all I got so far

ac_relays.jpg



Here's a pic woth the relay cut off. You can see the clip on the fender where it mounts in this pic

missing-relay.jpg


Relay will look like this

24955d1173729599-5-0l-engine-electrical-relays-wiring-help-please-2463784_46_full.jpg
 

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CoupeRon

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Sep 10, 2011
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Mike...that is awesome...can you just send me a pic of where those wires go as they get back close to the firewall? Do they plug into some connectors? I have all the other AC stuff which appears to be in place...I just dont se any signs of the wires you are showing....would think I would see something if they were cut out or removed...don't see any evidence of that..??? ugh
 

Mustang5L5

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Feb 18, 2001
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Only think I can think of is that on 1993 cars ford may have moved it elsewhere...but not finding reference to that on the net.

Is it possible the previous owner did a wire hiding mod and moved it into the fender behind the liner? Do you see wires going into the fender?

I can't take pic of my car right now as I don't keep it where I live.
 

CoupeRon

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Sep 10, 2011
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No...I checked for the wire hiding. I even pulled the inside fender well back. There are no wires in the fender whatsoever. The harness looks to be unmolested around the clutch cycling switch which is the only place I see a black and yellow wire. I have three connectors coming off the harness that are not attached to anything...but none have the colors that should be going to the relay. I really appreciate all the help.....Thank you Mike

Anyone else have any photos that could help??
 

Maryland Stang

Active Member
Aug 21, 2002
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There really isn't much to see there. The plug for the relay should be right there and I see no way of moving it to another area.

Here's a pic anyway of mine.

DSC01066.jpg
 

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CoupeRon

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Sep 10, 2011
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Thanks Maryland Stang! The wires that come out the bottom of it (the black square relay)......do they go back towards the harness by the AC Dryer (Black canister on the firewall) or do they go under the chassis..etc? I have spent hours trying to see where they may have come from (ie if some knuclehead cut them off or something), but I cant seem to find where they would have even originated or come into the engine compartment from. Seems like we are getting closer...if someone can just show me where the wires go from the relay......THANKS AGAIN to ALL!!!
 

Maryland Stang

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Aug 21, 2002
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The problem is that there are actually 2 relays right there (you can see the hex screw holding the second relay to the wheel well) with the second relay under the bundle of wires to the left. The wires for both relays appear to enter the harness and then go towards the firewall on the passenger side. Without removing my MAF (a complex job in it's self, nitrous and stuff) and opening the wiring harness up, it's virtually impossible to see where the wires go.

You're best off trying to find a Mustang at a junk yard and tearing it apart.
 

jrichker

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The wire colors identify the circuit function and number. Your best bet is to wipe the wires down with some mineral spirits until they are clean enough to clearly see what the colors are. Then post the colors and I will try to help you.
 

CoupeRon

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Sep 10, 2011
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Mike...that will be a huge help ref the pics. I called the closest junk yard today (45 mins away)...and of course....no 5.0s on the lot.
Jrichker...thanks....my problem is...I have no cut or loose wires.... WOAH...scratch that. I got frustrated and started yanking some of the sheething off and found a Black/yellow wire, white/blue, red, and pink/yellow wire hiding inside...obviously cut at some point and tucked back in the harness!! Is there a pigtail I can buy to connect these to so they can plug into the relay? Are they what I was looking for? Doesn't the relay have 5 wire connections??? Also...I have a white tube connector in same area..unplugged with light blue/purple and tan/white wires running to both ends....any reason it would not be connected??? THANKS a million guys...feels like I am close...no???
 

Mustang5L5

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Feb 18, 2001
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Can ypu tae pics pf what you've found at all?


I can't swing by my car til maybe tomorrow, but the WOT relay is 4 wires. On the first page of this thread, there is a diagram showing 4 wires going to the WOT relay. A Red, a black w/strpe, and two pink wires with stripes.

Sounds like the WOT relay was cut off?

If so, your best bet at this point is maybe find someone parting out a car that can snip you the harness with about 6" of wire to solder on, or head over to that boneyard. Other fords with 5.0s use the same relay.

I'll see if I can grab pics tomorrow