1uz aircon idle up

[Chris]

I got a 1uz in my toyota hilux. My problem is that i cant get the motor to idle up when i turn the aircon on, so as the hilux amplifier has a built in cut out when idle is too low. The 1uz idles at 500 rpm and hilux ac amplifier see this signal as too low and shuts off the compressor

also the compressor clutch signal wire is also wired into the 1uz ecu a/c circuit.

has anyone got a solution to this?

thanks

chris

[jzk25]

Turn the idle up on the throttle plate when the engine is at operating temp and then check that the idle switch is still on at closed throttle.

Is the ecu controlling the compressor clutch?

[CrUZida]

Disable the amplifier and have the AC button directly engage the clutch (via a relay)

[CrUZida]

Also, I was told that the AC wire for the ECU was actually an earth switch, not a +12v like the compressor clutch signal. So you'll need to run it through a relay to get it working.

That said, I've never bothered with an AC idle up on the 1UZ, it doesn't put enough of a strain on the motor to worry about it

[Kebin]

Disable the amplifier and have the AC button directly engage the clutch (via a relay)

Where's the safety in that? What stops the compressor from over pressurizing the system and blowing sh!t up when the condensor overheats on a hot day etc. etc.
You would have to run it through a pressure switch first.
Toyota a/c amplifiers are great, they work well and efficiently. Pity the 1u idles where it does in this case.
You could always run a signal multiplier to change the tach signal going to the amplifier and fool it but it wont solve the idle cutting out with blips of the throttle or clutching at the lights.

[CrUZida]

Excuse my ignorance, but what does the AC amplifier have to do with the pressures?

The low and high pressure switches are separate from the amplifier.

AFAIK the AC amplifier just controls the compressor (ie, turns it off if the water temp is too high, or if you are at full throttle, or the condensor gets too cold - unlikely in Aust ) controls the idle up, and not much else.

[Kebin]

In a hilux wiring diagram, the low pressure switch is connected to the amp. In other vehicles the pressure switches can be external. But all in all, a compressor should not be wired directly to 12v. Hence the need for hi/lo pressure switches thermostats thermisters etc. If you bypass the amp you lose these safety cutouts. If the factory design works reliabily and safely why change it?
This is purely a case of a v8 motor not working well with a 4cyl designed amplifier.

[CrUZida]

Fair enough, all the cars I've worked on the safety circuits have been separate from the amplifier.

When I said to have the button directly engage the clutch I did mean via the factory pressure sensors (ie find the wire that leaves the cabin and hook it into that.

Depending on the age of the car it may not even have a high pressure switch, just a low pressure cut out.

If the factory design works reliabily and safely why change it?

Perhaps because its not working in the manner he wants?

[Chris]

thanks for the tips guys

Cruzida we tried to give the ecu a negative trigger to try and get the idle up to work but still didnt work. The problem with my ute is that when the aircon is on the motor cuts out when the car is put into neutral.

Anyway i think i have fixed the problem by making the ute idle a bit higher by adjusting the throttle stop screw.

[CrUZida]

If you are running auto that will fuck up a lot of things.
If you are running manual its fine (albeit annoying)

[Chris]

yes running manual....thats why it cuts out.

It will just be for the times when its really hot in summer.

maybe later ill try hook up a VSV valve style of config.

[litldv8]

why not use something like a carbon canister purge valve across the throttlebody to idle up the motor when the compressor clutch is in
shouldn't be to hard
neil

[CrUZida]

Because the idle speed control valve will just lower the idle back to what it should be.
Where as cracking the throttle a little is effectively the same as putting your foot on the pedal, and so the computer doesn't compensate.
This introduces a whole new raft of issues if you are running the factory auto, but fine for a manual.


Chris, have you got the pinout for the amplifier?
Do you know which wire is the RPM wire?
What happens if you disconnect it?
If that doesn't work, get a Jaycar speedo corrector and multiply the signal by like 1.25 or so to stop it dropping the compressor out.
My old 4Runner did it the same thing (annoy the hell out of me) so I was going to try and disable the function, but ended up selling the car beforehand.

[Chris]

Because the idle speed control valve will just lower the idle back to what it should be.
Where as cracking the throttle a little is effectively the same as putting your foot on the pedal, and so the computer doesn't compensate.
This introduces a whole new raft of issues if you are running the factory auto, but fine for a manual.


Chris, have you got the pinout for the amplifier?
Do you know which wire is the RPM wire?
What happens if you disconnect it?
If that doesn't work, get a Jaycar speedo corrector and multiply the signal by like 1.25 or so to stop it dropping the compressor out.
My old 4Runner did it the same thing (annoy the hell out of me) so I was going to try and disable the function, but ended up selling the car beforehand.

yeah i got the pinouts for the amplifier and i know which one is the RPM wire.

I did try and disconnect the RPM wire to the amplifier and the compressor stops working, so it wont run without the rpm signal attached.

I just may try that speedo corrector. thanks