RPM occasionally fluctuates with AC Compressor on

[Andratch]

This is not necessarily a freon issue! I have had my car recently flushed and refilled but it’s the same as always. There IS an issue on the intake converted cars and REAL CSLs, no ones been able to find the solution yet LOL.

Out of curiosity, why is it only intermittent?

[0-60motorsports]

Out of curiosity, why is it only intermittent?

in my case its all the time. in the case of alpha n cars could be low freon....or something else. Like i said no one has figured it out yet as far as i know.

[dukeofchen]

20 years without refrigerant refilling and still this good, then I wouldn't waste money on doing system evacuation as this can be worst than what you have. Just add some refrigerant properly by checking the high side pressure with AC on.

there is no air in the system unless there is a big leak that all pressurized refrigerant had escaped and air entered. The refrigerant in the system is always exist in two phases: liquid and gas at any moment.

Good point, last thing I want to do is introduce risk of another issue when topping it off appropriately would suffice.

[L0okitzRaj]

I do not hear any relays clicking. I’ll try to get a flashlight on the compressor next time it does it to see if the clutch is kicking on and off.

which sensor are you referring to that could be bad?

AC pressure sensor.....

also, i should probably explain my experience with the other e46s, they weren't as frequent as your case. So potentially not related.

[inlinesix123]

Is this possible because the CSL m3 did not have AC? my car's idle dances in neutral with AC on with a CSL tune/airbox with map conversion. Mine's is quite annoying actually, it's consistently rev pulsing at idle.

[Andratch]

Is this possible because the CSL m3 did not have AC? my car's idle dances in neutral with AC on with a CSL tune/airbox with map conversion. Mine's is quite annoying actually, it's consistently rev pulsing at idle.

AC was an option. You could still get it. For me, the idle dance seems to be random. there are times when the AC is on where it's steady, and times where it pulses. Can't seem to figure out if there's a common reason why.

[inlinesix123]

AC was an option. You could still get it. For me, the idle dance seems to be random. there are times when the AC is on where it's steady, and times where it pulses. Can't seem to figure out if there's a common reason why.

No idea either, no CEL with the exception of an o2 cat that comes and goes.
This is really really strange. I might tune my revs to be 900-950 at idle, see if that does it. I HATE having to lightly hold my gas pedal to 1000rpm at every stop sign.

[Sylverlee]

Good point, last thing I want to do is introduce risk of another issue when topping it off appropriately would suffice.

Did you ever find the solution to this?

I have this issue on my 04. Was considering a purge and refill of Freon as well.

[0-60motorsports]

Did you ever find the solution to this?

I have this issue on my 04. Was considering a purge and refill of Freon as well.

Made no difference on mine. Some cars do it and some don't. Even Real some CSLs are like this.

[dukeofchen]

Did you ever find the solution to this?

I have this issue on my 04. Was considering a purge and refill of Freon as well.

Haven't gotten around to it yet unfortunately, but when I do I'm planning to get a set of gauges and top off to target pressure per Sapote's recommendation.

[Sylverlee]

Made no difference on mine. Some cars do it and some don't. Even Real some CSLs are like this.

Mine happens when in drive, idling. It’ll dip 200rpm or so every 15seconds. And then it’ll rebound. AC blows cold so the first shop said it can’t be low freon

also I would add my car is not csl converted.

[inlinesix123]

Mine happens when in drive, idling. It’ll dip 200rpm or so every 15seconds. And then it’ll rebound. AC blows cold so the first shop said it can’t be low freon

also I would add my car is not csl converted.

This is different from our behavior.
1. Not csl converted
2. happening while driving, our idle dances around while being stationary (think waiting for a light)

[lemoose]

To add more confusion to the mix, i have the same issue, except it only happens upon idling after a warm start- so never on cold starts, and doesnt occur anymore once i drive off. By show of hands here who is not only csl converted but also 6spd? That might be another variable to consider?

[Sylverlee]

To add more confusion to the mix, i have the same issue, except it only happens upon idling after a warm start- so never on cold starts, and doesnt occur anymore once i drive off. By show of hands here who is not only csl converted but also 6spd? That might be another variable to consider?

Mine doesn’t happen on cold start either. Once the engine is warm though, it happens at every stop light. I’m SMG

[Sylverlee]

Went to two bmw shops today.. they said it’s normal. Ugh. But they do hear the ac compressor unnecessarily cycling, although AC is cold throughout. A mystery. Guess I’ll be running the fan with no AC