JZX90 1JZ in MX83 air con idle up

[cybersimon]

Hi All,

I finally decided to get the air con fixed up on my MX83 Cressida having done an engine conversion about 18 months ago using a 1JZ-GTE from a JZX90 chaser.

As far as wiring goes I only had to connect up 3 wires in behind the glove box to get it working (will post up the wiring diagram I followed later). one of said wires comes from the ECU and is labeled "air con idle up", however sadly the car does no such thing when I turn on the air.

The car normally idles at about 900rpm, but when I turn the air on this drops to about 400rpm. Cruising along with the air on the car plays up a bit too, for instance I'll be sitting on 80 on a basically flat road and the revs will jump from say 2000 to 2200 then a couple of seconds later 2000, etc. It seems to accelerate fairly smoothly though.

Anyway, one thing at a time I guess - does anyone know what I need to do to get the engine to idle up when I turn the a/c on? Any info would be much appreciated.

[Bananaman]

I'm about to take a look at mine to get it working, any info you have would be tops

[cybersimon]

Update: It looks like the revs jumping problem isn't only when the A/C is on.
I just drove the car home from work and it does it even when the A/C is off, it just isn't as noticeable. So looks like I might have a separate problem, ISCV perhaps?

oh and Bananaman, will post some info later, is yours from a JZX90 as well? If so I should be able to save you some time :-)

[triptek]

It's a negative trigger on the jzx90 for ac idle up. So find the AC pin on the jzx90 pinouts. From memory it's pin 20 on the same plug as the ecu power(Batt/+B). Use a relay to trigger it to ground.

[cybersimon]

Thanks heaps triptek, I just tried that and it worked perfectly. I can't believe I didn't think of that earlier, I'm a bit of a wiring noob.
It also seems to have fixed the erratic reving problem. I guess you'd expect random behaviour putting +12v on that pin.

[cybersimon]

For anyone else interested here is the wiring diagram I used to hook the a/c up. I have added the relay bit for the idle up.

There is one other wire to hook up that isn't shown on this diagram, it gives power to the a/c clutch and will be located on one of the 3 grey JZX90 loom plugs that should be sitting in behind your glovebox (depending on how your conversion wiring has been done).

I found it by doing a continuity test between the wire on top of the a/c compressor and the JZX90 loom plugs. I think from memory it was on the smallest of the 3 plugs, and was lime green on my loom.

Anyway, when you find that wire, it also needs to be connected to pin 8 on figure 3 of the attached diagram, so that the a/c clutch gets +12v when the air con is turned on.

[Bananaman]

Yeah, my ecu is JZX90 at least, not sure about the motor itself. I'll get it gassed first, and then go from there.. Thanks for the info

[Hengsta]

Does anyone know if the two wire from the bottem of the air con compressor is needed to get it working? Or just need to wire in the magnetic clutch wire and it should be working?

Also what are the two wires for on the bottem of the compressor?

[cybersimon]

Also what are the two wires for on the bottem of the compressor?

I was wondering that myself. I didn't do anything with those 2 wires, basically just made sure that the clutch wire was getting its 12v and all seems well.

They might be designed to engage the fan on the condenser when the a/c is turned on. I'm only guessing though.

[chaserbuddy]

I was wondering that myself. I didn't do anything with those 2 wires, basically just made sure that the clutch wire was getting its 12v and all seems well.

They might be designed to engage the fan on the condenser when the a/c is turned on. I'm only guessing though.

well those two wires go to the ea2 plug on the jza70 loom and are apparently some sort of A/c speed sensor wires.

[turbo ke20]

The 2 wires on the bottom of the compressor are the speed sensor.

They will go to the oroginal a/c control module in the JZX90

Assuming that the MX83 dosen't have electronic climate control they wont be used.

All it does is send a signal to the a/c module and it compares engine speed to compressor speed and it will cut the compressor out if there is any eratic difference.

Ive nutted all this out on a 2jz supra to run a Haltech Platinum 2000 and using the original aircon system going through the ecu so it will cut out the compressor at a certain rpm and full throttle

[Hengsta]

[QUOTEturbo ke20;1268219]

Assuming that the MX83 dosen't have electronic climate control they wont be used.[/QUOTE]

awesome! That's what I want to hear

[litldv8]

i had a similar sort of plug on the 1uz hilux air compressor
the ls400 compressor i used had the climate control plug setup you are talking about
i had it gassed up and running but was not really cold was cool but that was it. the air con guy said that without that plug hooked up the compressor was only runnung at about 60% efficiency (what the climate control does) anyway took it off and he sent it away somewhere and had it removed (was a brand new effing compressor to start with) and now can freeze the nuts off a brass monkey
neil

[Z2TT]

Do all other 1jz ECU's use a negative trigger for the a/c, or only the JZX90 ?

[triptek]

I'v had a blitz jzz30 ecu require a negative trigger. Also the jzx100 is a negative. JZX81/JZA70 are all positive