Stop Start v Air Con

[NewtonHeath]

I have recently had a new condensor on my A4 to fix the aircon, but now the stop/start does not function.  The dealer is telling me that you cannot have both functioning at the same time, which sounds mad to me.  Does anyone know if this is actually true ?  I have turned off the aircon to test the theory, and the stop/start has become operational again, but this has never been the case in any other make I have driven

[Magnet]

Hello Chris,

Worth investigating a possibly below par battery? 
Kind regards,

Gareth. 

[NewtonHeath]

Hello Magnet.  Funnily enough, the battery was highlighted when I checked the car in, but when I picked it up he highlighted the air con v stop/start issue.  I assumed that he had tested the battery while it was in his workshop and ruled that out as an option.  I am running the car without the air con right now to test the theory, and the stop/start works.  Unfortunately, you then have to keep putting the blower on full to clear the windscreen.  Going forward, the air con will take precedense, so if it is a fact, then it is the atmosphere/local residents who will bear the brunt !!  I will however, go to my local Halfords this weekend and ask them to check the battery, just in case.

[Magnet]

Many thanks Chris,

Yes, Halfords can carryout a (more than basic?) battery efficiency text, but it may not be comprehensive enough. Other parameters (if not tested) such as cold cranking current can come into play. 
The dealer you was talking about in your first post - was that a main dealer? 
Kind regards,

Gareth. 

[NewtonHeath]

Hello Magnet.  No, but it was our local Audi.VW specialists so hopefully they know what they are talking about.

[Audi_Andy]

Ive an Audi A3  2013 onwards , when the aircon is on the stop-start doesnt work, when the aircon is off the stop start works.

[NewtonHeath]

Hello Andy. Yes, that is what the garage told me, but I find it hard to believe.  I have driven vehiclers from Renault, VW, Vauxhall and BMW and none of them have had this issue.

[Martyn W]

I've had several A4's & A5's, from a 2009 B8 to my current 2021 B9.5, over the last few years, & in all cases the air con & stop-start work in perfect harmony.

[NewtonHeath]

Hello Martyn.  Thank you for your comment.  I hope you are right and I am going to find my local Audi dealer and pose the question to them.

[FancyVW]

5 hours ago, NewtonHeath said:

Hello Martyn.  Thank you for your comment.  I hope you are right and I am going to find my local Audi dealer and pose the question to them.

A few weeks before the brake servo sensor failed on my A4 the stop/start stopped working and the aircon would cut in and out. There was a fault code stored, something to do with the engine requesting the compressor be shut down. All cleared up after the servo sensor was replaced. Worth investigating perhaps?

[NewtonHeath]

Thanks Duncan.  I think I may have to go to a garage and have my "codes" checked.  I have to get to the bottom of this as it is getting very frustrating now.

[jdragon]

Have you owned your car from new?

I don't have the details to hand but there's a VCDS hack that involes the stop/start and AC.

Is the light on the stop/start button when it's deactivated?

[NewtonHeath]

Hello Jon.  I purchased the car 2nd hand and it is nearly 5 years old. The light on the centre console is unlit at all times, but the little A on the dash comes on green when the a/c is off (and the engine cuts out) but comes up with a line through it when the a/c is on, suggesting I have disabled the system when in fact, I have not touched it.

[Magnet]

Hello Chris,

Did you get the battery checked after?

Re. Stop/start - Is it important to you that this system works, from an environmental point of view - or simply that ‘if it’s fitted it should work’? 
Obviously if it’s the former, then I must respect your views. If it’s the latter, then my view is that it’s an engineering averse system  ,and you are far better off without it. Maximum wear occurs on start up, and of course the additional wear on starter motor and battery is accelerated. 
For that reason, I have to remember to disable it on our non-Audi, every time I get in it! 
Kind regards,

Gareth. 

[jdragon]

18 hours ago, NewtonHeath said:

Hello Jon.  I purchased the car 2nd hand and it is nearly 5 years old. The light on the centre console is unlit at all times, but the little A on the dash comes on green when the a/c is off (and the engine cuts out) but comes up with a line through it when the a/c is on, suggesting I have disabled the system when in fact, I have not touched it.

Do you know the previous owner?

The VCDS hack to disable the stop/start will only work with the AC on. When the AC is off, the stop/start works.

I can understand why this may bother you. I'd be inclined to have someone with VCDS to check the module. Seems too much of a coincidence.

Like @Magnet I switch of manually because of same reasons. I also never have AC switched off, so the hack wouldn't be an issue, but I don't mind pressing the button.

This is where you will find in VCDS

 

[NewtonHeath]

Hi.  I live in a built up area with a lot of schools nearby so it is realy for environmental reasons I require it to work.  Once I head "out of town" am happy to turn it off. But, that is my choice (and I can press the button on the console to make it) and should not be the computer's.  Especially at the moment, the a/c has to be on to stop the car steaming up.

I shall check out tis VCDS thing once I find out what it is.

Thanks for all the comments/suggestions

[Stevey Y]

8 hours ago, NewtonHeath said:

Hi.  I live in a built up area with a lot of schools nearby so it is realy for environmental reasons I require it to work.  Once I head "out of town" am happy to turn it off. But, that is my choice (and I can press the button on the console to make it) and should not be the computer's.  Especially at the moment, the a/c has to be on to stop the car steaming up.

I shall check out tis VCDS thing once I find out what it is.

Thanks for all the comments/suggestions

Hi if it runs with adblue whats the problem better to produce Nox2 than rip up the starter and ring gear at just over £1200 just for the parts.

Steve.

[NewtonHeath]

Mine is a petrol, so no adblue involved.  Sorry, should have mentioned that at the outset.

 

[Magnet]

Thanks Chris,

I could well be wrong, but I have a feeling that the ‘if it’s fitted, it should be working’ principle has a slight edge over any other ‘reason’,  but it’s your vehicle, and you obviously have the choice of what you want from it. 
Kind regards,

Gareth.