[JeremyHenri]

I’m needing help with 2012 AC on my 12C. Car runs fine and idles fine around 700 rpm with AC off, the second I turn on AC, rpm’s jump to 1,100-1,200

Turn AC off, back to normal 700 rpm. Only jumps to really high rpm’s with AC on. AC still blows cold air, but was thinking maybe my AC is about to go bad or something wrong with AC causing this issue and maybe replacing the AC would fix this issue? Battery was replaced about 6 months ago and it was running fine last year with normal rpm’s, just need some advice. Thank you!

 

[360trev]

I’m needing help with 2012 AC on my 12C. Car runs fine and idles fine around 700 rpm with AC off, the second I turn on AC, rpm’s jump to 1,100-1,200

Turn AC off, back to normal 700 rpm. Only jumps to really high rpm’s with AC on. AC still blows cold air, but was thinking maybe my AC is about to go bad or something wrong with AC causing this issue and maybe replacing the AC would fix this issue? Battery was replaced about 6 months ago and it was running fine last year with normal rpm’s, just need some advice. Thank you!

Self learning wasn't done correctly.

Sent from my CPH2145 using Tapatalk

 

[JeremyHenri]

I’m new to the McLaren world so what is the “self learning” procedure or process and how does it work? Is this for all McLaren models or just the 12c?

 

[Hypurone]

The ECM raises the engine RPM to prevent it stalling under the load of the AC. He is prob referring to a learning sequence that can be done via the MDS (McLaren Tool) or similar diag tool to set how much the engine compensates when the AC is turned on...

 

[SJO]

I’m needing help with 2012 AC on my 12C. Car runs fine and idles fine around 700 rpm with AC off, the second I turn on AC, rpm’s jump to 1,100-1,200

Turn AC off, back to normal 700 rpm. Only jumps to really high rpm’s with AC on. AC still blows cold air, but was thinking maybe my AC is about to go bad or something wrong with AC causing this issue and maybe replacing the AC would fix this issue? Battery was replaced about 6 months ago and it was running fine last year with normal rpm’s, just need some advice. Thank you!

I’m thinking possibly the AC compressor could be part of the issue as well. Hopefully…it’s a simple issue, and you get it running properly!

 

[JeremyHenri]

Thanks for some of the advice y’all.

Can you actually program the ECM with the Mclaren tool to what RPM you want the car to idle at when the AC is on?

Does anyone on here have a new AC compressor for sale by chance as I do want car fixed soon as well.

 

[Macman500]

I’m pretty sure it’s normal for engine speed to increase with the AC running, especially considering the very low idle speed of the 12C. When I had my 12C I didn’t use the AC often but the engine speed always increased when it was turned on. It likely isn’t just for the engine but may be a result of certain AC system demands. I’m no expert but just providing my experience.

 

[JeremyHenri]

Yes I understand the idle speed goes up a little bit, but 1,100-1,200 rpm is excessive in my opinion. And that high of a rpm when it down shifts, it’s not very smooth downshifting at the high rpm’s


And the “self learning” can be done by this tool as well so it may just need to be “re learned” the computer? Is this done manually by the tech in a certain sequence?

 

[SJO]

I happened to run by this link for someone selling a 12C AC compressor at a pretty reasonable price. Just in case you may possibly need one for replacement.

2011-2014 McLaren MP4-12C A/C Air Conditioning Compressor OEM UNTESTED 00038897 | eBay

Find many great new & used options and get the best deals for 2011-2014 McLaren MP4-12C A/C Air Conditioning Compressor OEM UNTESTED 00038897 at the best online prices at eBay! Free shipping for many products!

www.ebay.com

 

[Hypurone]

Yes I understand the idle speed goes up a little bit, but 1,100-1,200 rpm is excessive in my opinion. And that high of a rpm when it down shifts, it’s not very smooth downshifting at the high rpm’s


And the “self learning” can be done by this tool as well so it may just need to be “re learned” the computer? Is this done manually by the tech in a certain sequence?

I would have to go and look in my system for it as I have never had that problem. But, if there is a relearn for it, it will be a Sequence option within one of the "modules", then next step is "Programming" it into the car.... MDS is a weird tool & process IMNHO...

You might wanna drop @ima2nr (McMedics) a PM. He spends a lot of time with the MDS tool!

 

[ima2nr (McMedics)]

I would have to go and look in my system for it as I have never had that problem. But, if there is a relearn for it, it will be a Sequence option within one of the "modules", then next step is "Programming" it into the car.... MDS is a weird tool & process IMNHO...

You might wanna drop @ima2nr (McMedics) a PM. He spends a lot of time with the MDS tool!

Hi Chuck,

I've actually spoken to Jeremy regarding this issue, and currently it has me stumped as well.

His RPM's are indeed excessive when the A/C is switched on, but it does not seem to be a vacuum leak according to his local technician.



Kevin P
Supercar Garage ATL - The McLaren Specialist
770-284-0172
Kennesaw GA
* Home of the flying McMedics... The only mobile McLaren Specialist! -We come to you!

CLICK HERE >>> www.SupercarGarageATL.com
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CLICK HERE >>> McLaren INTERCHANGABLE PARTS DATABASE !!!

 

[Hypurone]

Hi Chuck,

I've actually spoken to Jeremy regarding this issue, and currently it has me stumped as well.

His RPM's are indeed excessive when the A/C is switched on, but it does not seem to be a vacuum leak according to his local technician.

Just thinking outside the box here, but what if a Throttle Adaption is done on the off chance the values learned are incorrect? Remember, I had LOW idle probs and this cured the problem for me...

 

[ima2nr (McMedics)]

Throttle adaptations might be helpful, the question is does his independent mechanic shop have the correct diagnostic software to preform the sequences? If not maybe they need they invest in the correct diagnostic tools.

But lets keep the OP's question alive... because all suggestions are welcome for him right now....


Kevin P
Supercar Garage ATL - The McLaren Specialist
770-284-0172
Kennesaw GA
* Home of the flying McMedics... The only mobile McLaren Specialist! -We come to you!

CLICK HERE >>> www.SupercarGarageATL.com
CLICK HERE >>> DIYs: McLaren Do It Yourself Thread
CLICK HERE >>> McLaren INTERCHANGABLE PARTS DATABASE !!!

 

[JeremyHenri]

Thanks for the new information guys! I will ask this week if they can check into the “throttle adaption” as well and see if the computer could have incorrectly re learned the values as you have suggested. They do have the right tools as well as they use them on all of their race cars. They have even had a guy named Mike from Mclaren that came over about a week ago and he ran all of his software on the car and spent several hours on the car with no such luck. Mike has never seen this issue as well so that just why I’m reaching to all of you to have you helpful suggestions so I appreciate it!

 

[mrvex]

Its normal as stated above, pump increases load requirement hence increase RPM to stop the engine from stalling. I actually prefer it as stock RPM limit is too low for green purposes

 

[ima2nr (McMedics)]

Its normal as stated above, pump increases load requirement hence increase RPM to stop the engine from stalling. I actually prefer it as stock RPM limit is too low for green purposes

The OP's issue is not normal, his RPMs are raising up to 1100 -- 1200 RPM only when the A/C is turned on.

This is causing the transmission to hard shift on each "downshift" which is very uncomfortable and annoying.

When the A/C is turned off all is normal.

Kevin P
Supercar Garage ATL - The McLaren Specialist
770-284-0172
Kennesaw GA
* Home of the flying McMedics... The only mobile McLaren Specialist! -We come to you!

CLICK HERE >>> www.SupercarGarageATL.com
CLICK HERE >>> DIYs: McLaren Do It Yourself Thread
CLICK HERE >>> McLaren INTERCHANGABLE PARTS DATABASE !!!

 

[JeremyHenri]

Yes the downshifting is annoying and hard shutting down when slowing down as rpm’s are too high, that is correct Kevin, that is no fun!

Throttle adaption has already been done last week and didn’t help the issue. They are going to try changing out the idle speed controllers as they have some extra ones laying around the shop and see if this helps.

 

[mrvex]

Can you post a video please.. The AC RPM increases when turned on as per ecu programming. To determine if its normal or not, would need to see a video.. Hard shifts are mainly caused by paddle shifters being incorrectly setup or gearbox speed sensors.

 

[mrvex]

The ECM raises the engine RPM to prevent it stalling under the load of the AC. He is prob referring to a learning sequence that can be done via the MDS (McLaren Tool) or similar diag tool to set how much the engine compensates when the AC is turned on...

this.

 

[JeremyHenri]

Car is at speed shop so don’t have a video. The video wouldn’t matter at this point anyway because 1,100-1,200 rpm is way to high, no where near normal where it should be 😉