Strange Aircon Idle issue

[drgtr]

So my 2003 TD42ti has an odd idle behavior

Normal Idle 700rpm
Idle with Aircon 850

As you know the aircon compressor kicks in and out at intervals
In neutral when the aircon is running and its at 850rpm
If I press the pedal to rev up and let go. The idle rests like almost 1100rpm.

If I leave it alone and eventually the compressor stops the idle goes back to normal.
I can repeat this every time.

But If I don't touch the pedal the idle for aircon does its normal 700rpm and 850rpm when compressor cycles

[drgtr]

I think I worked it out.

Basically with aircon off. If I rev and let pedal go. It will return to 750 rpm everytime

So that rules out cable or binding.


Aircon on . Idle is increased as the actuator rod pulls on the bottom throttle cable plate which in turns pull on the top throttle cable.
So there is a constant position the rod holds the throttle in while the aircon compressor is on.
I believe this position from the rod is abit stronger than it needs to be. Not strong enough to pull further but strong enough
that if I press the pedal. The rod moves abit further so when throttle returns. Its in a slightly more opening position.


Makes sense as soon as compressor stops. The rod is released.

only way around is to adjust the aircon idle lower if I don't want that higher idle if pedal is pressed.

[Hodge]

Hey mate. Mine does the same.
Basically, on mine when AC is on and compressor clutch engaged and I rev it past 1000rpm, it won't go back down to it's "rest" idle of around 750-800rpm, until the next time compressor dis-engages. It's always done this since I've owned it, so I don't know whether this is standard or not.
I've had a thread here recently about AC idle adjust and while tinkering with everything, spraying everything with CRC etc, nothing has changed so I don't think any cable grab is tight or anything.

[drgtr]

Hodge.

Definately not cable tight or binding. As aircon off it returns to normal idle speed when you press the press the accelerator.

Its the Aircon Actuator L shape rod. It pulls the throttle cable arm. So if you press the accelerator the rod has no resistance so it moves abit further. So when the throttle cable arm does move back its resting at a slighly higher rpm.