F15 X5 - suddenly no heat!

[Andy_Kay]

I've got a 2015 X5 40e and suddenly yesterday it stopped putting out any heat in the cabin

Both sides upto max (28c) and nothing after 30 mins.
Weirdly on the return journey, the wife played around with something I think maybe changing the fan directions from all 3, to just face fans and suddenly we had heat. But then I turned it down to 21c then back to cold for the remainder of the journey.

Not sure if it's linked, but I got my FoxWell 530 and hooked it up yesterday for the first time and did a Transfer Case Reset/Calibration. Nothing else.

Is there a 'climate reset' feature on the ISTA system or something? Did the Foxwell ISTA do something? Heat was working fine for the 14 months I've had this X5

[c00lbeans]

Are the blue/red temp wheels between front vents set to red? I noticed the car has a hard time heating or cooling if those are set opposite to what you want.

[Andy_Kay]

Yep those are on red.

I never really understood those wheels anyway. Why have temperature set below yet these wheels above for hot/cold?

[Andy_Kay]

801253 error showing which I believe is to do with reduced power. Despite the 40e having 100% charge, it still doesn't heat

So I guess it needs a new 12v battery?
I have a Ctek charger which 'regenerates' batteries somehow, I wonder if I could connect it up to the 12v batt and see if it helps my heating issue

I read it's not an easy thing to change a battery in the 40e...

[///d]

Originally Posted by Andy_Kay

Yep those are on red.

I never really understood those wheels anyway. Why have temperature set below yet these wheels above for hot/cold?

Helps regulate temp without needing to rely on the auto setting. Auto doesn't always cut it in some climates. I can have my outter vents warm keeping windows and such clear, but center vents cool to help keep me cool. Also helps to stop the gf and her fires of hell temps from bleeding over to my side of the cabin.

[CatalinP]

The temperature setting on the HVAC refers to the average temperature for that side of the cabin, while the red/blue wheel regulates the air layers in the same part of the cabin. Red means hotter air in the upper layers, while keeping the same average temperature by supplying colder air at the bottom.

Read the owner's manual.

[Andy_Kay]

Originally Posted by CatalinP

The temperature setting on the HVAC refers to the average temperature for that side of the cabin, while the red/blue wheel regulates the air layers in the same part of the cabin. Red means hotter air in the upper layers, while keeping the same average temperature by supplying colder air at the bottom.

Read the owner's manual.

Thanks I never knew this. Useful.

Read a manual? I'm a man!

/although I did read the full (online PDF) manual of my R8 the week before got it, but that's a different beast

[RED_Y_]

Originally Posted by Andy_Kay

Thanks I never knew this. Useful.

Read a manual? I'm a man!

/although I did read the full (online PDF) manual of my R8 the week before got it, but that's a different beast

Reading the manual is highly recommended, a lot of little things a very well explained there including the dash dials and many other things.

[Andy_Kay]

Update: big battery in the boot was 12.4v so I've hooked up the Ctek for a recondition charge. The smaller battery on the right was 13.4-6v

[Andy_Kay]

Ctek charged the main (big) battery overnight, but as soon as I disconnected it, the voltage dropped to around 12.5v. So I guess its a new battery needed. I think I read on here that they only last like 4 or so years, and this looks like the original so it's done 6 years

Varta G14 019 ordered. Varta website says it matches the OEM part number 61217607983 so should be a straight swap.

I've got ISTA to do the 'new battery registration' thingy.

[CatalinP]

12.5V is 90% charged, your battery is fine...

[Andy_Kay]

Originally Posted by CatalinP

12.5V is 90% charged, your battery is fine...

Hmmm. I was getting 801253 error which according to https://bmwfault.codes/XMLDiagView?d...A1ADAAMwAwADQA
tells me 12v system is not sufficiently charged.

What else do you think is causing the no cabin heat issue?


Minor update: the wife rand the car in 'Save' mode, temps at 20c and we have heat! So I guess it is the battery regeneration issue - maybe car being used too often in electric only modes and it not recharging the 12V enough.

[Snowbird'sX5]

Our 12 v battery is charged via an inverter from the hybrid battery. So maybe the inverter has a fault ? Normally the system won’t ran the hybrid battery to 0 thus unable to charge the 12 v battery. Good luck !!

[///d]

My E90 had similar issues when it got cold. The battery tested fine, but when it was cold out it was affecting the cold cranking amps and was triggering power save mode because the car thought the battery was dying, which ultimately limits your HVC fan to low speed unless its on defrost. I replaced the battery thinking maybe it was still going bad, but still ran into the same issues and found it was a common problem with the E90, so I chalked it up to an over-sensitive battery monitoring system. The only time I saw this issue was when we got down to single digit temps (F) so I just kept the battery on a tender during the winter and that was enough to not trigger the power save mode. I brought it to the dealer and they couldn't replicate the issue because they always stored the car inside, or it was too warm out.


Assuming the 40e has the same type of monitoring system, you might still be getting heat even though it doesn't feel like it, its just a really low fan speed. If you turn defrost on and you suddenly get full fan speed, then the vehicle is in power save mode.

[Andy_Kay]

I've still not got round to changing the 12v battery yet. Still unsure of the procedure of telling it it's now 95a instead of 90a through ISTA

We're only getting heat when the car is used in 'Save' mode (petrol engine). If we attempt to use Max eDrive (elec only) we'll get heat for that journey, but then it won't give out any heat on the 'next' journey if that makes sense. So it's like it's only allowing heat if maybe the alternator from the petrol engine has been able to charge the 12v battery up, then next time the car starts, it checks voltage, then allows it. If heat has been used previous journey and only been on elec, it doesn't allow it - maybe this power save mode mentioned above? (complete guess - I have no idea).

I'll hopefully get round to changing the battery before the weekend, and report back if it's fixed it.

[Andy_Kay]

Originally Posted by Snowbird'sX5

Our 12 v battery is charged via an inverter from the hybrid battery. So maybe the inverter has a fault ? Normally the system won’t ran the hybrid battery to 0 thus unable to charge the 12 v battery. Good luck !!

very strange because it wouldn't pre-heat the car despite it being plugged in and at 100%

[Mikeliss]

Hi did you find issue cuz mine doing same just mine its petrol not hybrid. Im already changed battery but still no heat

[acmurda]

Check your coolant level. First thing to check with intermittent heat issues.

[Mikeliss]

Yes i did checked. Level its ok

[Clifton]

Originally Posted by Mikeliss

Yes i did checked. Level its ok

Something to try: Override fan speeds to max and set temps to hottest settings. If Heat comes back, it might be a faulty engine thermostat.

[///d]

Originally Posted by Mikeliss

Hi did you find issue cuz mine doing same just mine its petrol not hybrid. Im already changed battery but still no heat

Have you tried the windscreen defrost to see if you fans come on high and kick out heat on that setting?

[Amsterdave]

There is a common and somewhat particular issue with the hot water valve giving out after approximately 8 years on E70s and F15s, usually resulting in no heat on one side of the cabin, in particular when the car has been driven, stopped and then restarted again within a short amount of time.