bobbyhill

i am tring to figure out how to wire up ac in my truck with out messing anything up.my truck is 1995 4runner with swapped 3.4. any ideas?

UKrunner

From what I can gather, use 3.0 amp, leave all wiring as it was, except if you have an auto you need to bypass the water temp cut off switch (ground the pink wire) the wiring to the ecu goes to the similar pin names on the new ecu, AC1 and ACL I think. This will allow it to run but you lose idle speed up control and engine over heat protection. To gain idle speed up you need to turn a positive signal into a negative. The 3.0 ac amp uses a connection to ground from the ecu for idle speed up but the 3.4 ecu provides a 12v signal for idle speed up. Can be swapped very simply by wiring the 3.4 ecu output to coil of a relay with the other coil pin going to ground, and connecting the 3.0 ac amp to one terminal of the switch, and the other switch terminal to ground. You need a single pole normally open relay. Thus, when a 12v signal is sent by the ecu, it closes the switch and connects the ac amp input to ground.
The ac amp also needs an engine speed signal. You should have modified your tachometer with a 10K resistor. This also cures the engine speed signal to the 3.0 ac amp issue I think.

Please dont take any of this as fact. This is what I've done with mine but it's not charged yet so I cant verify.

Also, if you search, all the answers to getting ac running are actually in the 3.4 swap forum.

bobbyhill

what wires do i need to run to ecu and how many?my truck is 5 speed?does any one have the pin outs on the ecu?

thanks jason

UKrunner

Seriously?!
Down load everything you need from TIS.

Search for TIS before you ask.....

hamish_18

I am glad somebody has asked about this again hehe. I am also wanting to get my a/c going. I am looking at the diagrams now, and I don't see many differences, and was curious if it was as easy as pinning the two wires that went to the old ecu to the new ecu as you stated. Curious how the amp knows about engine rpm's though now that there is no ignitor. And I am also curious if that is what ORS did with their harnesses for the ac. If they added a relay to reverse the polarity like you explained. Simple idea really. I plan to get the new clutch for my 3.0 comp soon as its gonna hit 100 today, and I think I have procrastinated long enough I'll try to confirm what you did. I don't see why that doesn't work soo I am going to go into this being somewhat optimistic.

dntsdad

Jeff (Mosk) just posted what will become an valuable resource for ECM pinouts.

Download it and check it out.

https://www.yotatech.com/forums/f160...inouts-215718/

hamish_18

Well I just hooked everything up, and the clutch is not engaging. But the light on my A/C dash button comes on! hehe. So Any suggestions? Using 3.0 compressor, 3.0 amp, hooked the wire that goes to the amp and clutch that went to A/C on my old ecu to the AC1 of the new ECU. Then the wire that went to ACV on 3.0 ecu I pinned to the ACT of the 3.4 ecu. Is this backwards? I wish the EWD for the 90 4runner would tell me what each pin is for on the 3.0 amp. but oh well... I really would love to get this going if anybody can think of what I may did wrong...

dntsdad

DO you have this?
http://home.comcast.net/~dntsdad/aircond.pdf

Regardless, if you get it going DOCUMENT what you hooked up please and share.

hamish_18

Thats different than my 90's. But yes I have the EWD's for my year, and donor year. I checked the magnetic clutch by hooking it directly to my battery. It engaged just fine. So then I turned everything on, and checked the voltage of the output pin from the ecu. Both pins ACT, and AC1 do not have 12 volts. I do notice that the 3.4 amp has a wire directly to the clutch, where the 3.0 amp just has a splice going from the ecu to clutch to amp. So maybe the new ecu simply doesn't supply the amp with its power.. It almost looks like at least for the 97, that the power comes from the 10A fuse through the Dual pressure switch and then into the amp. I am going to wire in a relay and switch for the clutch, and manually engage it to see if everything works. If it does, then I will wire it in with the A/C switch or something... So it engages when I push the A/C switch.... Will report my findings after this is done..

dntsdad

Vital??

vital22re

iTrader: (2)

i went with the 3.4 amp hooked up the leads from the ecu, crossed over and hooked up the hi/low pressure switch and the thermosister. Gave it a charge and its working for me with r134

hamish_18

hmm well there is like only one junkyard open today, but they have a 96 and a 97. Will the 3rz motor have the same amplifier as the 5vz models?? I think the 96 had the 4cyl in it. So did you have to get the harness for it? or are the plugs the same? ugh, why can't anything be simple lol. its a 100 today! I want a/c!! LOL...

hamish_18

And the junkyard closed at like 3:00 them bastards! At any rate, I think I know why its not working. I started troubleshooting everything per the FSM. I found that the dual pressure switch has no continuity. Meaning its open. The thing should be closed if the system is more than 30 psi and less than some high number. So I shorted those to wires together. Started the engine up, and pushed the a/c button with the fan on. Voila, Clutch engaged and I could hear the amp click on. Of course I didn't let it run but a couple seconds, as I would imagine there is nothing in the system, or very little. The stupid ass kid I got the runner said that the a/c worked when he had it running. Whatever, I guess I get to go try and get it charged. I never broke the system when I was swapping motors, I just laid the compressor off to the side. Only other thought is that the pressure switch is not working anymore? Which sucks because it looks like I would have to break the system to get to it. UGH....

dntsdad

cool. document, document, document!!

vital22re

iTrader: (2)

sounds like you're making good progress!

UKrunner

I still havent got mine charged yet. Might do this today and report my findings.

hamish_18

so apparently you can't get r12 anymore? So I guess I get to get that conversion kit and replace the o-rings etc... and go to r134a. Unless I can get somebody to charge my system with r12. Either way this I will be spending more money than I wanted for the a/c. And I will document on this, as I haven't been able to find concrete documentation of what to do. Everybody says something different.

UKrunner

Yeah. Napa has the O ring kit for $78 and there are dozens and dozens of O rings to replace. You can buy HC12 if you can find it. Its R12 compatible so you dont need to replace your rings. Also, call around your AC places, some still have R12 for classics and such.

I'm putting r134a in and will use the a/c until the seals go then replace them over winter and do a proper conversion job.

dntsdad

Is there a diagram anywhere that shows all the various orings and sized that would be need to convert?

UKrunner

I dont know of a diagram, but I searched A/C on napa's website and came across a pic of the kit.

I found a r134a kit containing the fittings and oil required to change the a/c over. $27 plus a can of refrigerant for $12 and I now have nice cold air conditioning for $40. I measured the air temps coming out the passenger side vent on full blower, non recirculating. Started at 90 deg F and cooled to 53 deg F in about 30 seconds.

I bypassed the a/c amp and just connected 12v to the compressor clutch to get the thing charged. Took about 20 - 25 minutes to pull the conversion oil plus a can of refrigerant. I tested the a/c amp and am not getting a signal to the compressor clutch.

I havent yet put in the relays to reverse the ecu signals which I want to try asap. I will also take a look at the tach signal and see if it looks clean and is at the right voltage level. And I'll also take a look at the pressure switches and see if there is 12v present at the input to the amp. The only thing left would be the thermistor.

If anyone is doing this on a car that originally had an auto ecu, you must ground the pink wire from the water temp switch. To test this, start the car, turn on the a/c switch and when you touch the pink wire to ground you will hear a relay click in the a/c amp.