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Idle with AC problem


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My a/c on my skyline turns on and off, An airicon mechanic said it was and idler problem. It only does this on idle. At times the revs fall though the floor, and sometimes stalls the car. Even @ low revs. It's quite dangerous cus sometimes it stalls the car when im driving along and i change gear, and the dies on me.

I've been playing around with the aac plug and cleaned it.

The problem is intermittant. So it's hard to tell if it is fixed or not until l8r.

Think the AAC could be hald stuffed not sure though.

Where the best place in brisbane to find parts to fix this?

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I think i know what the problem is.

Today I cleaned out the AAC valve and the part of the plenum where AAC connects to, was gunked up. 2morrow will tell if my cleaneing job was sucesfull.

the AAC valve control the revs when car engine is on load. I think it basicaly sets the revs higher when it is on load, but becuase on load it keeps revs relatively the same.

Well, That's what i've figured out 2day. yesterday I would not have a clue what it done.

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went to an Aircon guy 2day, and He siad not 2 bother regassing till u fix the idle problem. It's still has gas, but the aicon guy said to give it a top up.

Well I done a quick clean of the manifold where the AAC calve connects 2. It seams to do it more in the heat. I'll see how it behaves tomorrow.

Thanx Dave, I'll b keeping that in mind.

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Heres another possiblity-

Check pin 9 on the ECU. This is the air conditioner idle-up input. When you switch on the air conditioner, it will pull this pin to ground (zero volts). This triggers the idle up sequence that opens the AAC valve to supply a bit of extra power to the engine at idle.

When you switch off the air conditioner, this pin should rise to 12v (open circuit)

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Is this the AAC valve, or just one part of it. what do u call the bit it bolts on2. what does the IAC valve look like?

I need to adjust my normal idle up to, sits on 600 rpm now, use to be 800 rpm.

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I'll check ECU mayb 2morrow. I also looked at my AFM 2day, looked ok. So might have another look at the AAC valve? or what i think is the AAC valve.

I never lubed it up last time, I remebr looking into the manifold bit bolts up 2, actually took it of and cleaned it out. There was a spring in there somewhere 2, think it was on the back of the screw.

How do I change the Idle speed. there's 2 screws that u adjust, one on the back of AAC and Where's the other. Also hear u fine tune the normal idle on the back of the ECU on a pot.

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It only likes to stall after it's warmed up and driven around a bit, turned off than on or just after a while in stop start traffic. mainly on very hot days.

I thought that lack of gasses the compressor would actual have an easier job and would most likely try to rev higher because there is not much gas to compresss. Dont know. I'll keep it in mind, since it only stalls @ idle with the A/C on.

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  • 1 year later...

Hey wow it's one of my old posts.

Yeah I manage to find the problema and fix it. (It still plays up every now and then but usualy been quite good). One method to get it working when it plays up is to accelerate up in the 5k 6k mark.


I changed the AAC unit.. or actually IAA unit (not sure what is what when it comes to the names off it)

which stands for well AAC is something like Auxilary Air Control i think or something like that.

What it does is when the engine is on load at idle it will turn on and componsate adding a bit of revs by changing amount of air feedback. Now what happens when u get bellow a certain Idle point the computer goes Oh crap what's going on were loosing power better turn stuff off and turns off is the a/c.

What actual happens is that one of 2 things happens .. or both.

1. the seal inside the unit actually just wares out and leakes air.

2. the spring becomes compressed and does not rebound back to it's orignal point therefore not responding quick enough to componsate load.

I went to zoom and bought a second hand unit for about $90

now if i remeber it was something like $600+ new from nissan.

Also there are two type of the unit that fitted on the r32. but not sure for the r33.

The unit can be found at the back of the plenum. it has a 2 pin connector with a solinoid. Also as 2 air pipes running into it and should have an Idle adjustment screw. And like a bolt on module to the plenum.

U can take it off and clean it out and usualy the gasket does'nt brake. I've played with 2 now and still have both gaskets ok.

Just a clean out show some improvement on my r32. Alot of carbon builds up inside the unit.


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no worries..

it was a long time of playing around.

But eventualy i found the main problem to be the unit.

I hope it works all out. Drives me nuts when you a/c does not work in summer.

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