RPM unstable when the AC is on

[Rick_new]

Hello All,

I recently purchased a new 2023 CX-5 Select (non-turbo) in Houston, USA. The car currently has 150 miles on it. I noticed that when the AC is on, the rpm fluctuates between 500 and 750 at idle. That is, the rpm will fall from 750 to 500 and then go up to 750. I don't know what is causing the rpm to be unstable. In my previous car, the rpm was always stable at idle when the AC was on. Is it normal for rpm to fluctuate in the CX-5? If not, what should I do to fix it? Sorry, I am not knowledgeable when it comes to cars.

Thank you for your time.

Rick

 

[wlong01]

I assume that only happens at idle. Most cars will fluctuate a little when the compressor kicks on but 250 rpms seems a little much. I notice my 2016 Touring with NA engine hardly ever fluctuates but my 2019 Reserve with Turbo does a little more but nowhere near 250 rpms.

You may want to take it back to the dealer and let them look at it.

 

[paris1]

Hmm; Houston, TX. Currently 100+ degrees every day. don't be surprised if the dealer tells you that's within normal range for idle rpm with A/C on.

 

[gazelle]

I noticed RPM issues once, and it was not just on idle. I suspect it was after some lousy gas station. I filled it with 93 once, and didn't have this issue again after that

 

[yrwei52]

Hello All,

I recently purchased a new 2023 CX-5 Select (non-turbo) in Houston, USA. The car currently has 150 miles on it. I noticed that when the AC is on, the rpm fluctuates between 500 and 750 at idle. That is, the rpm will fall from 750 to 500 and then go up to 750. I don't know what is causing the rpm to be unstable. In my previous car, the rpm was always stable at idle when the AC was on. Is it normal for rpm to fluctuate in the CX-5? If not, what should I do to fix it? Sorry, I am not knowledgeable when it comes to cars.

Thank you for your time.

Rick

Based on Mazda Factory Service Manual with automatic transmission the idle speed range should be 550 ~ 650 rpm, and 650 ~ 800 rpm with AC on. The idle will drop a bit when the AC compressor kicks in, but should go back up to the previous rpm. Your 250 rpm drop seems too much and not normal. If your idle is “unstable” and keeps going up and down between 500 ~ 750 rpm, then it’s not normal either. Try to turn the AC temp control to the lowest (60°F) to keep the compressor running and see if the idle is still fluctuating.

I’d try @gazelle suggested above, wait until the gas tank is empty and fill it up at a reputable gas station with top-tier gas such as Shell or Costco and see if it improves.

 

[Koko_Bandit]

With 150 miles on the engine, it is not broken in. The owner's manual says 600 miles for break in. We noticed a difference in smoothness, etc after the first 1,000 miles on our '23 CE.

 

[skid00skid0]

The AC compressor probably needs 3-4 HP to start up. The engine probably only *makes* 2-3 HP, to spin itself at idle. It takes time for the throttle plate to open up a bit when the compressor kicks in (or is it *just* a valve?). So-yeah, you get a dip in idle speed. I've never owned a vehicle that didn't drop revs when the AC kicked on.

It should only be a problem if the engine then stumbles, because idle rpm is too low.

 

[q1054521247q]

Hello All,

I recently purchased a new 2023 CX-5 Select (non-turbo) in Houston, USA. The car currently has 150 miles on it. I noticed that when the AC is on, the rpm fluctuates between 500 and 750 at idle. That is, the rpm will fall from 750 to 500 and then go up to 750. I don't know what is causing the rpm to be unstable. In my previous car, the rpm was always stable at idle when the AC was on. Is it normal for rpm to fluctuate in the CX-5? If not, what should I do to fix it? Sorry, I am not knowledgeable when it comes to cars.

Thank you for your time.

Rick

when I bought the car. I notice the problem too. dealer said it's normal but mine is around 800-670 at idle when ac is on. now 60K miles on the car still like that. idle on parked it will keep jumping around that range. This car is a bit different from other cars that I owned before. other cars do not seem like the compressor is on and off repeat, rmp will stay at 750-800.

But your 800-500 that's a bit more I would say that's not normal.

Based on Mazda Factory Service Manual with automatic transmission the idle speed range should be 550 ~ 650 rpm, and 650 ~ 800 rpm with AC on. The idle will drop a bit when the AC compressor kicks in, but should go back up to the previous rpm. Your 250 rpm drop seems too much and not normal. If your idle is “unstable” and keeps going up and down between 500 ~ 750 rpm, then it’s not normal either. Try to turn the AC temp control to the lowest (60°F) to keep the compressor running and see if the idle is still fluctuating.

I’d try @gazelle suggested above, wait until the gas tank is empty and fill it up at a reputable gas station with top-tier gas such as Shell or Costco and see if it improves.

I am just outside of San Antonio it's 104 outside now. I did just try right now putting the car on 60F. it's still like that. keep kicking 800-670ish about every minute at idle.

 

[yrwei52]

⋯
I am just outside of San Antonio it's 104 outside now. I did just try right now putting the car on 60F. it's still like that. keep kicking 800-670ish about every minute at idle.

The idle of my 2016 CX-5 is steady at 750 rpm with the AC on, no fluctuation.

 

[wlong01]

The idle of my 2016 CX-5 is steady at 750 rpm with the AC on, no fluctuation.

My 16 Touring is like that too but our 19 Reserve flucuates some but not to the point of annoyance.
Worst was my wife's CR-V. That thing always bounced around to the point it became nerve wracking.

 

[q1054521247q]

The idle of my 2016 CX-5 is steady at 750 rpm with the AC on, no fluctuation.

very interesting. I will try it again later when I go out. it's not to the point that annoys me

 

[veritas80]

Mine does it a little too. Nothing crazy

 

[Rick_new]

Thank you all for sharing your experiences. It is a relief to know that it is not uncommon for rpm to be unstable at idle in the CX-5. I will fill up at my trusted gas station and see if there are any improvements. My older car had a steady rpm, and hence I was a little worried.

 

[Rick_new]

when I bought the car. I notice the problem too. dealer said it's normal but mine is around 800-670 at idle when ac is on. now 60K miles on the car still like that. idle on parked it will keep jumping around that range. This car is a bit different from other cars that I owned before. other cars do not seem like the compressor is on and off repeat, rmp will stay at 750-800.

But your 800-500 that's a bit more I would say that's not normal.


I am just outside of San Antonio it's 104 outside now. I did just try right now putting the car on 60F. it's still like that. keep kicking 800-670ish about every minute at idle.

I see the same in my car. RPM fluctuating between 800-650 every minute at idle. As you pointed out, it is the compressor turning on and off that causes it.

 

[sergioregra]

Hello All,

I recently purchased a new 2023 CX-5 Select (non-turbo) in Houston, USA. The car currently has 150 miles on it. I noticed that when the AC is on, the rpm fluctuates between 500 and 750 at idle. That is, the rpm will fall from 750 to 500 and then go up to 750. I don't know what is causing the rpm to be unstable. In my previous car, the rpm was always stable at idle when the AC was on. Is it normal for rpm to fluctuate in the CX-5? If not, what should I do to fix it? Sorry, I am not knowledgeable when it comes to cars.Nox Vidmate VLC

Thank you for your time.

Rick

Most cars will fluctuate a little when the compressor kicks on but 250 rpms seems a little much.