Stop start and climate control faults

[Bikergonebald]

Hi all
6 weeks ago I bought a 2021 arona FR 1.0 with 29,000 miles from a main dealer. Full service history with them.
The stop start system has never worked. We took it back after 2 weeks and they said the battery wasn’t charged enough because we did short journeys. They charged it for 4 hours and told me to charge it more, which I did for 17 hours.

still no stop start, I commute 50 minutes twice a day and at the weekend do two x 2 hr motorway trips. I charged it again and used an OBD reader and found after 18hours on a battery optimiser the battery was 80%, after a 2 hr drive the battery was 76%

the car never charges itself to over 76%
I also noticed on a long journey that the climate control wasn’t working, it was getting hot and wasn’t even trying to blow cold, I set both controls on low and it blasted out cold air. I set it at 17 but it kept getting warmer so I opened the windows. Now we’ve noticed on cold days it doesn’t warm up unless put on high, again it isn’t even trying, the fans barely run.
We took it back to SEAT and they charged the battery to 100% and said the stop start worked. It hasn’t in the 3 days since despite driving 4 hours on a motorway.

for the climate they said it takes time to react. I guess they think it’s operator error.

now my questions
Could the two faults be linked.?
Has anyone had similar problems where no faults are recorded?

thanks
Kevin

 

[RUM4MO]

I don't think that the two issues are connected.
First the battery not charging up to a high level - that is intentional as controlling the battery charge level to under 80%, i don't know the exact design intended %, always makes sure that there is adequate "head room" for any/all "braking regenerative charging" and that means that under engine braking, or slowing, there will be a bigger load allowed to be put onto the alternator to minimise energy wastage.

The heating/cooling issue, this sounds quite a lot like being an issue with temperature control flap motor(s) feedback potentiometer, ie the area the wiper is contacting the track on the feedback potentiometer, in normal use, is slightly dirty so the flap motor is not sending its present position back to the temperature control circuit. One way to prove/disprove this, is to demand Hi wait a minute, then demand Lo, then demand Hi again each time waiting a minute. Repeat that maybe 10 to 20 times and that should clean up the feedback track enough to allow for better control for a week or a month - or maybe longer.
If you had a proper OBD diagnostic tool for VW Group, like VCDS, you could watch the response and so work out if initially it was not working as intended, and after doing what I have suggested, you would be able to see if control had improved. Doing this does not sort out every flap motor though.

Edit:- even with the battery being fit for use and the charging being okay, the running conditions must be "okay" to allow for auto Stop/Start, ie if you are demanding a lot of cabin heating or cooling, and the car is not at the correct temperature, then there is a need for the engine to be kept running to heat the cabin using engine coolant, or using the AC compressor.

Having said that, maybe there is a connection between the two issues after all!

Maybe try living with the AC and heating fan switched off for part of a journey to see if auto Stop/Start works, the battery might need to be given a health check to see if it is still fit for use.

My wife's August 2015 VW Polo 1.2TSI's battery is just still the original EFB Exide battery, and it is still okay in use and still checks out as being in quite good health, during lock down I made sure that it was connected to a battery maintenance charger frequently. Our younger daughter bought a used 2019 Arona 1.0TSI 115PS, and its battery let them down within 6 months of buying it, that was back in October 2023 after buying it in June 2023 and not using it much!

 

[Bikergonebald]

Hi Rum4mo,
Thanks for your reply. i will try driving it with the AC and heating completely off to see if it makes a difference. If it's the temperature control flap i'll be shocked, my daughters 2004 polo has that fault. I had expected that in 20 years VW would have fixed it

Incidentally, i had a VW T-ROC hire car this week. The stop start and climate control worked perfectly. While i've been away my wife said our car is still not working right. I will be calling the dealer to book it in when they have a curtesy car available and i won't be handing that back until it's fixed. Or they can refund my £15k. I wonder if that will focus their attention on fixing it.

 

[RUM4MO]

Yes, the flap motor nonsense does go back many years, back to before 2000 I think! I had the temperature one go faulty in my 2000 VW Passat 4Motion, it could be coaxed back into use for short periods, but on one trip back up from being down to Oxford or Canterbury, we had to stop maybe 3 times to let the cabin cool down enough to be okay, so that forced the issue and I finally fitted that new flap motor that had been stored in the boot for maybe 8 months! That car even had a sunroof, but having that open was still not enough to dump the excess heat out in a warm day!

 

[Bikergonebald]

Time to give an update.
It has now been back to the SEAT dealer 3 times. The first time they charged the battery to about 90% - no change.
The second time that had it longer and charged it to 100% - no change.

this time they had it for a week and in the Friday changes the battery. The stop start worked that evening and part of the next day. Now two days since we picked it up it’s not working despite a 300 mile drive.

On the climate control we’ve come to the conclusion it’s just a badly designed system. The courtesy car they gave us was exactly the same, anywhere between 16.5 and 29.5 the fans stay at the lowest. So it seems it best to set it manually rather than automatic.

I’ll be phoning the dealers again tomorrow about the stop start.

 

[RUM4MO]

I have noticed that some times, with my wife's 2015 Polo 1.2TSI SEL - so that means it has auto HVAC, that the fan tends to run at slow speeds a lot, and sometimes it feels a "bit cool", but as you say that will be down to poor/marginal/cheap design, plus these cabin temperature control systems use a "sunlight" sensor, so quite often that causes the heat input to get reduced, which is good at certain times of year but not always, especially in winter. Now and again I consider making sure that the "sunlight" senor is covered just to see under varying outside temperature conditions, if this extra control sensor helps or hinders the cabin temperature control.