1UZ Variable A/C Compressor Wiring

Frank Clark

Member
I've decided to add A/C to my race car (OK, call me a wimp). Have a Vintage Air unit. Mounting of the Sanden compressor would be problematic. So I am planning on using the Toyota compressor. This is on a VVTi 1UZ.

The A/C compressor has electronically variable vanes (as well as a clutch).

Any ideas on how I need to apply signal/power to the plug to force the compressor to max output?
 

gloverman

Well-Known Member
I have done lots of engine swaps with a/c and use an early pump of gen1 or gen2 and wire clutch only. Easy as.
 

Frank Clark

Member
Does the early pump bolt on the same mount? I'm in the US and have checked early model LS400, SC400 and the Toyota Tundra (2UZ). All the compressors look like they have the solenoid for electronic variable vanes (in addition to the clutch).

Can you point me to a specific compressor?
 

gloverman

Well-Known Member
As I'm in Nz we we mostly JDM stuff. Im doing a 3uz atm with the right pump so will attempt to shrink the photo to upload here. It was of a UZZ30 soarer.
 

George_R

Member
Stock or aftermarket ecu? (idle up options depend on this)
As for flow control valve, I use aftermarket pwm controller available in local radio hobby store. It's reported to have fragile coil winding that overheats and burns if you feed it with constant 12v
 

Frank Clark

Member
Aftermarket with IAC and manual TB.

I have spare PWM outputs. I think they are rated at 2a. Also have spare inputs, so if I need to monitor temp and adjust PWM up/down that should be straight forward.
 

George_R

Member
Constant PWM is ok from my experience
So you use one as on/off for the clutch relay, another one for constant pwm when a/c is on and that's pretty much it
 

Frank Clark

Member
The car has no insulation, door seals or side windows so max all the time would be great. I wonder what the max equates to and how to figure out which pins are which.
 

George_R

Member
By testing for resistance and knowing what you have there (lock sensor, mag.clutch, pressure control valve)
Safe pwm value is 50%
 

Mat Grant

Member
Hi, I've got an early Denso AC compressor on a 1992 1UZ with the 40/40/40 pin ECU. I have just wired 12v to the mag clutch off a relay from the AC button / climate control in the car. But I have not sent any connection from this to the ECU, the idle does drop significantly when the AC is engaged, please can anyone tell me what pin I should send the AC 12v to tell the ECU the AC is on?

Sorry for the thread hijack :)

Cheers, Mat.
 

Frank Clark

Member
The ECU actually grounds the PWM signal, so it seems the easy solution is to connect the clutch+ to the PWM+, and PWM- to the ECU. Then ECU can always provide 50% signal and turning the clutch on/off will actually power the clutch and the control valve.

Sound reasonable?
 

Mat Grant

Member
Hi Frank,

Thanks for putting up the link, I have that diagram, just not clear on which is the input to the ECU.

Mat.
 

gloverman

Well-Known Member
I had my lastest gased up this week . Its a vvti running an early soarer (sc400) non-vvti pump. Only the clutch connected and its working well. I couldnt find any numbers on the pump sorry.
 

Mrme4u

New Member
The ECU actually grounds the PWM signal, so it seems the easy solution is to connect the clutch+ to the PWM+, and PWM- to the ECU. Then ECU can always provide 50% signal and turning the clutch on/off will actually power the clutch and the control valve.

Sound reasonable?
I am currently wiring a 3UZ in my 1998 Mitsubishi Pajero.
What is the meaning of PWM?
I am using the 3UZ Compressor but it's got a 3 wire plug.
1. 2 wires coming from the clutch one immediately grounded to the compressor body
One wire goes to the 3 wire plug.
I understand that I connect the clutch wire to the ECU.
And at the same time to the AC Relay?
If yes which pin of the AC Relay do I use?

What do I do with the 2 other wires coming from the compressor
 
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