Wiring JDM a/c to WRX harness??

[chudlo]

Does anyone know how to get a JDM a/c compressor to work with WRX(USDM) wiring harness?

I am doing a V8 swap into my 02 wagon and it seems that I have to use the JDM compressor as it is MUCH smaller than the WRX one.
The problem is that the JDM compressor connector seems to only need one maybe two wires.
The WRX compressor uses 3 wires.

Now looking at the Manual for the WRX there are 3 connections and aside from the clutch to relay, I cant figure out why the other 2 wires are necessary. There is a thermal protector and a pressure switch associated with the other 2 wires, But I cant figure out how the JDM compressor works.


Anybody made theirs work?

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[chudlo]

anyone want to guess?

[neko]

guess? sure. if i can wire motor swaps i can guess wiring. and this guess is based on my experience with making the a/c work in a 00 RS with an 03 RS motor:


well the US compressor itself(from 03 WRX and 03 RS from what i know) uses only one wire for activation, and the other two wires just loop together. Hence the 3 wires.

Now the older RS (2000 model) uses 3 wires. one for activation and two that run a pressure/thermo switch of some variety. so the big difference is that the newer compressor just doesn't use this switch at all. in fact the hole for the switch is still there, but not drilled out, on the newer compressor body. perhaps its a safety so the older compressor won't run without something in the system, but the newer style doesn't need it? don't know that answer, not super important.

what is important is how many wires it uses, and what the pattern is in the plug on top of the compressor. one big issue with the 00 -> 03 is that the pattern of wires in the switch reverses. the activation wire (blue) moves from the top to the bottom and the light green or yellow wire (depending on year) to the sensor (actually the gnd from the sensor to the ecu if i know my wiring colors well enuf) moves to the top. the green w/red power for the sensor stays in the middle.

so. if you follow that perhaps you can figure out how to get the right wires to the assembly. do you need the switch, or can you just loop those two sensor wires no matter which compressor you use? i'm not sure about the ramifications of that, but i'm sure it can be done. i would wire the sensor if its on the compressor you use, if you can.

[chudlo]

Thank you for the input!

I will read over that a few times.

I have looked at my 2002 USDM WRX manual, and it shows a "Thermal Protector" being part of the loop you referred to. It then carries on to a "Pressure Switch".

So the new/JDM compressor doesnt have the "Thermal Protector" inside like my USDM compressor.

I was worried that it was a necessary part of the circuit.

[neko]

its just a cutout switch, AFAIK. in a worst case, you just loop the two sensor wires, like the 03 is naturally, and it makes the ecu happy. if you have a compressor without the sensor, then i assume that means that compressor has some other sort of safety or can run without pressure.

[chudlo]

Thanks for your help neko.
I just got back from the dealer and the Tech said about the same thing as you. The other tech said that the sensors were going bad in the compressors and they had to remove it from the wiring anyway.

So I will just loop it as you siggested and that should be fine.

[gling]

Bump from the dead. Anyone make this work? I have a JDM ECU as well and it seems that the connection between the A/C button in the dash and the A/C compressor no longer exists. This leads me to believe that the ECU intercepts the signal from the button on the dash and the compressor itself (I tested it with a multimeter). I thought of wiring the JDM single-wire A/C compressor to the battery directly and activate it via a relay and an independent switch but then I thought about the ramifications of having the compressor on all the time as opposed to the modulated engagement.

Anyone else have any suggestions or ideas before I pull out the whole A/C system (again) and just go for a reversed intake manifold? I'd rather not since I appreciate having A/C sometimes.

[chudlo]

Did you try the above advice?

I did get my a/c to work. It seems that you are doing a V8 swap into an 02? You should be able to get it working by following the advice above. It was not neccesary for me to change any ECU wiring to make the a/c work.


Did you take the dash apart? Maybe something is loose? Did you test the switch itself?

[Mulder]

You are correct that the ECU controls the compressor. The switch is an input to the ECU, and there is an output that drives a relay to power the compressor.
If you wired the switch to the relay directly, not only would you lose the ECU-related functions for the compressor such as WOT and low ambient temp cutout, but also the fans would not run because they are also ECU-controlled.
I'd suggest checking the wiring diagrams and pinout info for the JDM ECU, it could just be a matter of the AC control being on a different pin from the USDM unit.

[gling]

Originally Posted by chudlo

Did you try the above advice?

I did get my a/c to work. It seems that you are doing a V8 swap into an 02? You should be able to get it working by following the advice above. It was not neccesary for me to change any ECU wiring to make the a/c work.


Did you take the dash apart? Maybe something is loose? Did you test the switch itself?

I don't see how the above advice would help if there is no signal at all that is being sent to the A/C compressor via the WRX harness (I checked with a multimeter). But let me think about it a bit more and look at the wiring on the harness again.

Also, are you using your USDM or the JDM ECU?

Originally Posted by Mulder

You are correct that the ECU controls the compressor. The switch is an input to the ECU, and there is an output that drives a relay to power the compressor.
If you wired the switch to the relay directly, not only would you lose the ECU-related functions for the compressor such as WOT and low ambient temp cutout, but also the fans would not run because they are also ECU-controlled.
I'd suggest checking the wiring diagrams and pinout info for the JDM ECU, it could just be a matter of the AC control being on a different pin from the USDM unit.

The fans work and so does the heater. It's just the engagement of the A/C compressor. I think it is a matter of slightly different wiring for the JDM ECU since it has an auto HVAC whereas my WRX has the standard HVAC.

I can't seem to find the pinout/wiring diagram for the JDM ECU though. Anyone know where I can obtain one?

[Zephyr]

From what I can tell the pressure switch is located on the compressor on the USDM version, on the JDM it is located off the compressor.

[chudlo]

Originally Posted by gling

I don't see how the above advice would help if there is no signal at all that is being sent to the A/C compressor via the WRX harness (I checked with a multimeter). But let me think about it a bit more and look at the wiring on the harness again.

Did you loop the wires at the compressor that need to be looped?

Originally Posted by gling

Also, are you using your USDM or the JDM ECU?

New Zealand one actually. lol

Originally Posted by gling

The fans work and so does the heater. It's just the engagement of the A/C compressor. I think it is a matter of slightly different wiring for the JDM ECU since it has an auto HVAC whereas my WRX has the standard HVAC.

I can't seem to find the pinout/wiring diagram for the JDM ECU though. Anyone know where I can obtain one?

If I am remembering this all correctly, and it is now 4 years hence so maybe I don't, there was no need to rewire anything inside the car. My ECU is also set up for automatic control.

[gling]

Originally Posted by Zephyr

From what I can tell the pressure switch is located on the compressor on the USDM version, on the JDM it is located off the compressor.

Thanks for responding Zephyr. I'll go search for said pressure switch tomorrow.

Originally Posted by chudlo

Did you loop the wires at the compressor that need to be looped?



New Zealand one actually. lol





If I am remembering this all correctly, and it is now 4 years hence so maybe I don't, there was no need to rewire anything inside the car. My ECU is also set up for automatic control.

The compressor only has one lead off of it. I'll go double check tomorrow and take some photos too.

[chudlo]

Originally Posted by gling

The compressor only has one lead off of it. I'll go double check tomorrow and take some photos too.

OK. I keep forgetting things.

USDM Compressor= more than one lead.
USDM wiring harness @ compressor= one lead to compressor other 2 are looped

JDM wiring harness= one lead
JDM Compressor= one lead

Now, I took the USDM connector off and replaced it with the single lead JDM connector. Then I took the two wires that are used for the pressure switch and connected them.

I believe this is all I had to do.



teh chud

[gling]

Originally Posted by chudlo

USDM Compressor= more than one lead.
USDM wiring harness @ compressor= one lead to compressor other 2 are looped

JDM wiring harness= one lead
JDM Compressor= one lead

Thus far I follow.

Originally Posted by chudlo

Now, I took the USDM connector off and replaced it with the single lead JDM connector. Then I took the two wires that are used for the pressure switch and connected them.

If I assume and follow correctly, you took the three-lead connector off the USDM WRX wiring harness and replaced it with the single-lead JDM connector. As for the wiring, you connected one of the three USDM wiring harness leads to the single-lead JDM connector (which one?) and looped the other two leads from the USDM WRX wiring harness.

If that is correct, I follow you. However, the one lead that is supposed to activate the A/C compressor (not related to the pressure switch) does not show any signs of voltage change. I checked all three USDM WRX leads for voltage change (with respect to a ground) before and after I pressed the A/C switch in the center console and none showed a 12 V source/change.

At this point, I am inclined to think it is an issue with a different pin(s) designation(s) between the USDM WRX and the JDM STI ECU.

Cheers.

Gerald.

P/s: Chad, thanks a bunch for taking the time to respond to this thread; I greatly appreciate it.

[gling]

OK, sorry for the delay guys. I finally got time to go get some images.

Below is the JDM A/C condenser with its single-wire connector and to the right right of it, the USDM WRX three-wire harness connector.



A close-up of the JDM A/C condenser connecter:



And the USDM WRX connector with each lead labeled 1, 2, and 3 respectively for ease of identification.



Last but not least, here are the matching connectors off of the JDM wiring harness and the USDM A/C compressor that I salvaged. The leads on the USDM WRX connector off the A/C condenser itself are labeled a, b, and c. When the USDM WRX A/C compressor is connected to the matching wiring harness, the connection is as follows:

1 - a
2 - b
3 - c



Now, all three leads off the USDM wiring harness do not show a change in voltage when checked against a ground before and after the A/C button in the center console is pressed. Hence, I believe it is an issue with the different pin designation/wiring of the JDM STI and USDM WRX ECU. Unless, as Chad mentioned, connecting/looping wires on the harness(es) will make a difference.

[gling]

Bump for more information.

[chudlo]

Have you soldered the two wires together that are looped in the stock harness yet? there is no point testing anything until you have accomplished that. If it doesn't work from there, continue trouble shooting.

Here is a pic of my connections,though everything is covered in tape/shrinkrap.

http://picasaweb.google.com/lh/photo...eat=directlink

In a previous PM, I sent you my phone number incase you have questions.


teh chud

[gling]

I get what you mean now Chad; basically connecting terminals 1 & 2 together and using terminal 3 to connect to the A/C condenser. I'll go give it a shot and report back.

Thanks.

Gerald.

[gling]

Chad,

Connected as you directed but no dice; the A/C compressor does not engage I really think it is an issue with the ECU now. I'll fiddle around with it more later.

Cheers.

Gerald.

[johan84]

hello i have

bought a fulll jdm engine to put in my vw bug

i have also a question about the sensors are all the usdm europeen en jdm sensor en solenoids the same because i'm missing al the sensors that are not on the engine

can i buy the somewhere aftermarket?

and i have seen that the engine have 2 oxygon sensors in the exhaust a rear and a front sensor when your remove the catalyst do get some problems with these sensors

and how about the fuel temperture sensor that is in the or by the fuel pump are also in a aftermarket full pump like a walbro are do have to get the orginal sensor?


greetings johan

[jaybirde978]

on a off beat, you have a lo psi & hi psi both need condnuity for associated relays to function,


Jay

[gling]

Originally Posted by jaybirde978

on a off beat, you have a lo psi & hi psi both need condnuity for associated relays to function,


Jay

Jay,

Could you please elaborate a little more on this matter?

Thanks.

Gerald.

[Krang]

Did you ever resolve this gling? Anyone else have any ideas? I am having the same problem.

I pinned the blue wire and looped the other two, which I believe is correct?

[gling]

Originally Posted by Krang

Did you ever resolve this gling? Anyone else have any ideas? I am having the same problem.

I pinned the blue wire and looped the other two, which I believe is correct?

Yeah, there is a pressure switch in the system. Go get your AC charged up and you it should start working. The compressor won't turn on unless the system is charged up.

Cheers.

Gerald.