revs droping when AC is on (197)

[trile]

turned the AC on full blast yesterday, the air-con compresor started whining soon and I noticed that the car was idling at lower revs.
I reved it a bit and when I released the pedal the revs droped a lot (below idle) and the car juddered.
Happened every time I reved the car and the AC was on.Revs drop, engine judders and then they go back up.

the engine was warmed up, 40 degrees outside...

???

Happened last summer on a few occasions too

 

[Groovejunkie]

That'll be because the Aircon draws all it's power from the engine... !! If you're just idling then most things will drops the revs very slightly... headlights, fans etc etc!!

 

[trile]

i know the AC draws power but surrely what I explained can't be very normal?

Every time I turn the AC on and drive I notice the lack of power etc but this was different.Like the engine was about to stall ( like when you release the clutch pedal too much)

 

[Chrisjk]

Very normal, if i have the fan on number 4 when pulling off from idle, i have to rev more otherwise i pull of like a learner driver.

 

[stephen1985]

dont worry its normal mate

 

[foxspeed]

revs shouldnt drop excessively - revs drop on mine when ac is on but then they come back up and settle to a steady idle

 

[trile]

here's a vid of what happens..
it's a shame you can't 'see' how the engine judders.
revs drop almost to 500 rpm.
that CAN't be normal :nono:

[YOUTUBE]Lx0mvo_RB8s[/YOUTUBE]

 

[Fastchip]

Seems a little low. What is your A/C pressure reading ?

 

[H182]

If i switch the AC on whilst idle the engine revs drop and it shudders a little but after a second it goes back to where it should. Doesn't constantly idle lower like that.

 

[Shaunyboy]

normally the idle control should compensate for the AC being on, mine doest have a prob with aircon on, if its new take it back to renault as it should be warrentied, if you have concerns get it checked.

 

[Fastchip]

If i switch the AC on whilst idle the engine revs drop and it shudders a little but after a second it goes back to where it should. Doesn't constantly idle lower like that.

Idling on the 197 is more stable than on the older types.

 

[foxspeed]

if they drop to 500 only when returning from when you revved it up and the idle is steady then that should be ok - mines does that to a certain extent - its only the ecu stabilising the revs once they have come down

 

[trile]

Seems a little low. What is your A/C pressure reading ?

I'll check that