Rough idle when ac is on

[Robnguyen0802]

Wondering if anyone had ran into a rough idle when the ac is on. Car is in neutral and when I turn on the ac the rpm dips. This will happen every minute or so.

some history on my car is it’s a 2003 and a manual. Car has 80k. Just got the vanos done, changed the spark plug, and had the valve adjusted. Noticed this started happening after this was done.

[Cubieman]

I get a bit of stumble in the idle when my AC is turned on. I never really noticed it before until I went with CSL software. I have no clue why that would make any difference whatsoever.
Your AC clutch creates a parasitic draw or a drag effect on your accessory belt an thus your engine. Generally speaking most modern cars at idle shouldn't have a terribly rough idle when the AC is turned on although you still may notice some effect. If it is really bad you may have a bad clutch/bearings on your AC unit.

Also you say the RPM dips are happening every minute or so. Simply sounds like the the AC is cycling on/off at regular intervals which is completely normal, there is a pressure switch built into the AC system that will tell the unit when to turn on/off the clutch.

Is it possible you just started to use the AC recently? And thats why you are noticing it after the service items you listed?

Edit: You may consider posting this in the general section where it will likely get more views.

[Arith2]

My wife's 2010 Sonata does the same thing. My dad's 2018 F150 does this too. I think it's just normal operation for a lot of cars. My car did this back when I had the system charged. If it's dipping really low, then you my have a vacuum leak or something(just speculation). Check STFT and LTFT but I wouldn't be worried if nothing really jumps out at you. If car was out of time enough to mess up idle, you'd have a code.

You used NGKs plugs right?

[Robnguyen0802]

My wife's 2010 Sonata does the same thing. My dad's 2018 F150 does this too. I think it's just normal operation for a lot of cars. My car did this back when I had the system charged. If it's dipping really low, then you my have a vacuum leak or something(just speculation). Check STFT and LTFT but I wouldn't be worried if nothing really jumps out at you. If car was out of time enough to mess up idle, you'd have a code.

You used NGKs plugs right?

Thanks for the info. Yes I used NGK plugs.

Here is a video of what I’m referring to regarding idle drop when the ac is on.

https://youtu.be/G-ZdqBl69MQ

[Maxima SE]

Wondering if anyone had ran into a rough idle when the ac is on. Car is in neutral and when I turn on the ac the rpm dips. This will happen every minute or so.

some history on my car is it’s a 2003 and a manual. Car has 80k. Just got the vanos done, changed the spark plug, and had the valve adjusted. Noticed this started happening after this was done.

you could be low on refrigerant

[Arith2]

That is a bit more severe than what I'm referring to. that's a 400rpm drop. If it's only been a few days the car could still be adapting if the adaptations were wiped. My car has been slowly idling better and adapting still after 3 weeks of them being erased. My cold start used to be garbage and it would bump up to 1500, drop to 500, then stabilize at 1100. Now it just jumps, doesn't drop much and stabilizes quickly. Something stupid like a plug could have the wrong torque on it. Definitely looks like a misfire from the video but I wouldn't say it definitely is without more evidence. An A/C check wouldn't hurt but it could just take time the engine to readapt.

[Robnguyen0802]

That makes sense Arith2. I’m gonna reach out to the guys to see if they wiped anything out. I’ll keep you guys posted. Thank guy.

[Pavlo]

I had a similar issue when the throttle bodies were getting dirty. The idle valve starts to bypass more air than it needs to and cylinder 3 and 4 were a bit too lean (was able to see it on Rough Running values in INPA). Problem only showed itself at idle under higher than normal load, basically AC on only. Don't think this is a coding/programming issue.