S13 SR into S14, anyone got ac wiring working?

[g6civcx]

It has codyace's bracket so the S14 KA compressor fits. Now I'm trying to get the wiring to work.

Got any info to get me started?

Searching just reveals people asking the same question.

[Homer_Simpson]

From GSRacer
" on the f3 conector (big white plug under dashboard near passenger foot well , you know the one you have to splice into to make your engine swap work) you need to splice together the following cables pin 16 yellow/ black to pin 43 or 46 (cant remeber now im at work) black/pink. and what do you know voila it works, push the a/c button a/c turns on, pust it again it turns off."

This is what I did, except I spliced in the wires for the IACV and the hi/lo fan. This us using the KA compressor.

[g6civcx]

There is so much going on in the AC system that I'm not even sure what the thermo amp does, or the ECU for that matter. Tying the thermo amp output to the ground pin of the triple pressure switch works?

[Homer_Simpson]

I did exactly what GSracer said and it worked. It was later that I added the fan and IACV, still worked where IACV kicked up the idle every time I hit the switch.

[codyace]

I wish I knew more in regard how to wire it up, but I soruced my wire harness from Wiring Specialities (Yuri) and the A/C has worked since day one. I tried splicing into a IACV wire to help trigger the high idle aspect of the car with AC on, but never was able to make it work :/

There was a nice thread on FreshAlloy also involving AC wiring, but it's been so long that I've since lost the bookmark I had for it (ultimate AC thread IIRC it was titled)

[Homer_Simpson]

Official SR A-C thread!!!! come on in - Page 3 - FreshAlloy.com Forums (http://forums.freshalloy.com/showthread.php?p=1298191#post1298191)

[g6civcx]

If you can help me figure out how the S14 thermo control amp works, I can confirm his design, or recommend something else.

Right now I can't figure out how the thermo control amp works on the S14.

If you tie together pin 43 Black/Pink and pin 16 Yellow/Black on the F3 plug, you may as well unplug the thermo control amplifier since this doesn't protect you from overfreezing.

[Homer_Simpson]

If you can help me figure out how the S14 thermo control amp works, I can confirm his design, or recommend something else.

Right now I can't figure out how the thermo control amp works on the S14.

If you tie together pin 43 Black/Pink and pin 16 Yellow/Black on the F3 plug, you may as well unplug the thermo control amplifier since this doesn't protect you from overfreezing.
Unfortunately I do not know how the thermo control amp works. However, in the link above those guys did mention this potential problem as well as some theories as to how to fix it. Good luck.

[g6civcx]

I know how the thermo amp works on the S13, but on the S14 it's more complicated. The ECU has 2 pins going to the thermo control amp on the S14.

I can do this really easily if I can just figure out what the thermo amp is doing.

Anybody else?

[Ceepo]

All you have to do is solder the #16(Black/Yellow A/C Switch) to the #43IBlack/Pink Triple Pressure Switch) and it should work... i know mine does...

You dont need to mess with any of the other wiring, just do as i told you and it should work, you can remove the A/C wiring from the s13 redtop harness as the s14 a/c system is in the body harness and not the motor harness... you can remove all the redtop wiring besides
Keep all of these plugs:
1.ECU
2.Dash Plug(f3)
3.Relay
4.Ignitor
5.Wiper Amp
^in cabin
------------------------
6.Wipers
7.Coil Pack
8.Knock Sensor
9.MAF
10.CAS
11.O2
12.Injectors 1-4
13.Water Temp
14.TPS
15. IACV(idle air control valve)
^engine side of harness

http://img.photobucket.com/albums/v46/om1kron/My%20Cars/1996%20240sx%20Kouki/2008-11-29%20-%20Harness/f3plug95240sx.jpg

Hope the helps any more questions PM me, i just did my harness a month or 2 ago...

[g6civcx]

Do you have freezing protection? What other pin did you connect to the ECU for the AC?

[Ceepo]

I didnt connect anything to the ecu, just jump those wires together on the dash plug and the a/c works... if you want to try and get all the a/c stuff wired up you can but seems to much work lol, i havnt had any issues with it, my a/c is ice cold all the time i use it...

[g6civcx]

my a/c is ice cold all the time i use it...

I don't mind not having FICD and acceleration cut, but I want the freeze-over protection and pressure protection so there won't be damage.

I'm about to try something. I'll post up if I can get everything working like stock.

Connecting pins 16 Yellow/Black and 43 Black/Pink on the F3 plug completely bypasses the thermo control amp. The AC compressor will cycle regardless of evaporator temperature.

I would like to prevent freeover if at all possible.

[g6civcx]

I also found a discrepancy in the FSM. The HA diagram labels F3 pin 16 Yellow/Black going to ECU pin 9 A/C & DEF SW. F3 pin 45 Orange/Black is shown going to ECU pin 12 PD SW.

The EC diagram labels ECU pin 9 as Orange/Black air conditioner triple-pressure switch. Pin 12 is Yellow/Black and goes to air conditioner hand power switch.

I have to check the F3 plug now to be sure. I have no idea which section in the FSM is correct.

[Ceepo]

i was also wondering about the to much pressure problem, but i dont usually use my a/c unless im in vegas...

[g6civcx]

i was also wondering about the to much pressure problem, but i dont usually use my a/c unless im in vegas...

The thermo control amplifier shuts off the compressor if the evaporator gets too cold so you don't have overfreezing.

The triple pressure switch shuts off the pump if you have too little or too much pressure.

The way you said to do it would retain the triple pressure switch to protect against pressure extremes. So you're okay there for pressure protection.

[g6civcx]

Ceepo, Homer, Om1kron, and others with S13 SR into S14.

I think I figured out how to make this work just like stock if you're using the S14 compressor on codyace's bracket.

Does any of you want to try? I'll post the wiring. It's quite simple actually.

I just need to figure out where the FICD diode is located.

[Krusty_s13]

im going to do this soon too so id like to see a write up

[g6civcx]

im going to do this soon too so id like to see a write up

$20. You pay now. No refund!

:p

[codyace]

I just sent a PM as well (not that I needed to, im' odd) but I'd rather do this right now that you may have potentially sorted it out. Again, Iv'e never had such issues (have an AC machine) but would rather have it setup correctly....

I'm going to be redoing AC over the winter (new passenger side lines to move the drier to a better location) so I'll redo the wiring too.

[g6civcx]

I have the info for a 96 because that's what I'm working on. I'm not sure if it carries to other years but it should give you an idea.

I'm working on posting the wires.

[g6civcx]

There are two electronic protection circuits for the AC.

The thermo control amplifier knocks the compressor off when the evaporator gets too cold so you don't overfreeze. The S13 has only one wire from the ECU to the thermo control amp. When the AC button is pushed and the fan is turned to 1, 2, 3, or 4, the thermo control amp gets power from switched current.

The S13 SR ECU gets a ground signal to pin 41 Blue/Green. This pin sees ground when the compressor should kick on and nothing when the evaporator is too cold or the AC/fan is not turned on.

The S14 also has a triple pressure switch. It knocks the compressor off when coolant pressure is too high or too low. It sits on the ground pin of the AC relay and knocks the relay off and on as needed.

The triple pressure switch also kicks on the condenser fans as needed.

The other two components are the Fast Idle Control Device (FICD) and ambient termperature switch.

The FICD kicks up the idle when the compressor is on and ambient temp is low. The ECU also samples the ambient temp and it looks like the ECU can kick the compressor and idle as well if necessary.

[g6civcx]

I am almost ready to go on this. I need one of you guys to test out this one wire on the recirculation relay since I don't have the car here.

On the F3 plug, pin 37 Orange/Blue is the ground pin of the recirculation relay. What happens when you stick this wire to ground and activate the recirculation relay? Does it do anything? How about with the recirc button selected? What if you changed the modes around?

I think what it does is cancels recirculation mode when you select DEF or Defrost/Feet, but I haven't tested this yet.

So if any of you guys have an S14 handy, please try this out and let me know what it does.

[g6civcx]

Alright, here we go:

http://www.nguyenconsult.com/zilvia/wire/s13sracins14.jpg

Reference this thread: http://zilvia.net/f/engine-tech/293028-ultimate-s13-sr-wiring-guide.html

1 - F3 pin 37, Orange/Blue, goes to S14 ECU pin 114 "PAIR" - apparently this triggers the Recirculation relay and sends a signal to the push control unit. I still haven't quite figured out what the push control unit does with this, but several experienced wiring guys told me cut and remove

2 - F3 pin 46, Orange/Blue, goes to S14 ECU pin 21 "THERMO AMP" - thermo control amp, this wire sees ground when it's ok to activate the ac compressor, connect to S13 SR ECU pin 41 Blue/Green

3 - F3 pin 16, Yellow/Black, goes to S14 ECU pin 9 "AC & DEF SW" - this wire sees current when the AC and/or DEF mode is selected, cut and remove

4 - F3 pin 43, Black/Pink, goes to S14 ECU pin 15 "A/C RLY" - allows the ECU to trigger the AC relay if the triple pressure switch detects that refrigerant pressure is within range, connect to S13 SR ECU pin 106 Green/Yellow, this wire can be found in the brown plug by the battery on the S13 SR engine harness, run this wire back into the F3 plug

5 - F3 pin 45, Orange/black, goes to S14 ECU pin 12 "PD SW" - this wire sees ground when the triple pressure switch triggers the condenser fan, cut and remove

6/7/8 - this part is a little complicated so I'll discuss them together.

The Fast Idle Control Device is used to kick up the idle when the compressor is running.

The ambient temperature switch kicks on when air temp is below about 72-77 F*.

The diode prevents current from going backward through the FICD.

The FICD receives power whenever the AC compressor is activated. Power travels through the FICD, through the diode, and to the S14 ECU AND the ambient temperature switch.

The ambient temp switch activates the FICD when air temp is low. The ECU also gets a read on the air temp switch, and I believe the ECU can also kick on the FICD if needed by showing ground on this wire.

You need to source a diode since the S13 SR engine harness doesn't have a diode. The diode is located on the S13 and S14 KA engine harness. Clip it and wire it in.

The diode allows current to travel one way but not the other. It's a one-way switch for current. Use your multimeter and check. One way shows continuity. The other shows nothing.

Power comes into the FICD via the Blue/Green wire. This wire is found at the Big Grey Plug. This wire needs to be rerouted into the dash. Connect this to S14 F3 pin 44 Blue/Red. Power will be provided when the AC relay is tripped.

Note that the S14 has the compressor wiring on the body harness. The S13 SR has the compressor wiring on the engine harness. If you follow the Blue/Green wire, you'll see that it has a 1pin plug. This is for the S13 SR AC compressor. You can remove this wire from the harness because it is not used on the S14. The S14 (and LHD S13s) run the AC wiring on the body.

Hook the diode up to the FICD ground Blue/Red found at the small grey plug by the battery. Make sure current can flow out of the FICD but not in.

The diode is then tied together with the S13 SR ECU pin 45 Blue/White, both wires connect to the F3 pin 29 Blue/White wire.

9/10 - F3 pin 25 Orange/Blue and pin 41 Blue/Green, goes to S14 ECU pin 13 and 14 "RF RH" and "RF RL" - these wires control the dual condenser fan. cut and remove.

If you do all that correctly, the AC should work just like stock. Good luck.

[brn2slid]

wiring specialties claims that you should not have to do any of that to get it to work like stock. Who did your harness swap?

[g6civcx]

wiring specialties claims that you should not have to do any of that to get it to work like stock

I haven't talk to Yury yet, but a lot of people just hardwire the AC button to the AC compressor.

They bypass the thermo control amp completely. It will work but it won't give you thermo control amp.

They also bypass the FICD to turn up the idle when the compressor is running.

I would like to see how anyone keeps the thermo control amp and the FICD without doing what I did.

Who did your harness swap?

I've been a computer engineer for 10 years now. I do all my own wiring, but I do check up with different people from time to time.

[brn2slid]

I was just curious, they seemed pretty sure that it would work just as it always had, but you are talking about wiring under the dash, something they obviously do not touch... I almost gave them 300 to do my conversion, but I may as well do it myself now. Thanks for the write up though, let us know how it turns out

[g6civcx]

All the wiring on the S14 is done at the white F3 plug. You don't need to touch any other harness on the car to mate the engine harness.

I still recommend you pay someone to do your wiring though. Even though you may know where each wire should go, it's a lot more complicated in practise.

Better to pay if you don't plan on spending a lot of time to do it properly. Not worth your time if you're not going to be doing swap after swap.

[MudRacer]

Sorry to bring this thread out of the dead. But did anyone try this all out and got it working?

[Magnoliarichj]

I have a wiring specialties harness and the ac does not work. I'm looking into this as well