Heater problem - Can you help?

[Bigscreen]

2005 Z4 Alpina Roadster S.

I was driving around last night with the climate control set to manual and the heater control knob set to about half way, all of a sudden I noticed hot air was no longer evident through the dash grills although the fan was still running and blowing air.

The only way I could get hot air to flow was by turning the temperature knob to its maximum, turn it just one notch back and it goes cool (Ambient, not air con cool) but again the fan was still running.

Tried it in auto mode and no difference. Seems like the temp control knob is faulty or is it something else?

Thanks in advance for any advice.

 

[jamiez]

I had the same issue, dealers ended up replacing "something" related to the heater controls under warranty.
They provided no paperwork, otherwise i would get the part number for you

 

[lacroupade]

Does your fan work on all speeds or is it stuck on 'low'? If so, it could be the infamous 'shipping mode' (can't remember the proper name for it) that has been known to kick in either spuriously or as a result of a flattening battery. £35 for a dealer to unprogramme (plus a new battery if that was the case)....

 

[Bigscreen]

Does your fan work on all speeds or is it stuck on 'low'? If so, it could be the infamous 'shipping mode' (can't remember the proper name for it) that has been known to kick in either spuriously or as a result of a flattening battery. £35 for a dealer to unprogramme (plus a new battery if that was the case)....

I'm 99% sure I tried fan speed knob and fan was running fast or slow dependent on position. Will double check tonight. Just seemed odd that hot air would only come out at very hottest temp setting, but just turn knob one tiny notch back and hot air disappears :?

 

[lacroupade]

Hmmm could be a thermostatic problem of some kind but no idea where sensors are....but do check fan speed as that shipping mode thing is easily fixed.

 

[Bigscreen]

Yep double checked tonight and fan speed works fine, and guess what? So does the heat control :headbang:

I was driving for an hour or so last night before this problem occurred so will have to go out for another drive soon to see if I can replicate it...... Any excuse

Still welcome any ideas as to what the problem may be, even though it now appears to be intermittent.

 

[Mini Zibb]

I just bought my 2.5 the other day and am having the exact same problem. All other controls work fine, just for any hot air, either air con or not, needs to be on maximum. 1 turn back and it is quite cold. Mine is not intermittent though, so need to get it sorted quickly. Thanks for the help.
Tristan.

 

[Bigscreen]

I just bought my 2.5 the other day and am having the exact same problem. All other controls work fine, just for any hot air, either air con or not, needs to be on maximum. 1 turn back and it is quite cold. Mine is not intermittent though, so need to get it sorted quickly. Thanks for the help.
Tristan.

Interesting. Tristan could you keep the thread updated if anything specific is found please?

 

[Mini Zibb]

Will do, I am going to give my spare key a go because i have a feeling it didnt have the problem with that one. Will let you know if anything asap.
Tristan.

 

[srhutch]

On the E46 which the Z4 is based there was a 'hedgehog' (resister) that used to fail, not sure if the Z4 does have one but it could be the problem.

 

[Mini Zibb]

Thanks srhutch, is this resistor easily accesible, and if so how do i know its broken. TIA.
Tristan.

 

[srhutch]

It used to be easy to get to on the E46, but as said I'm not sure the Z4 has the same one, or it may have a revised model without the issue.

Can't help any more than that I'm afraid

 

[Bigscreen]

Thanks for the reply srhutch, but I believe the symptom both Tristan and I appear to be having is different in that it only effects the heat setting needing to be on full to get hot air from any vents with the fan running normally.

My understanding of the 'hedgehog' (resister)problem relates mainly to erratic fan speed and air distribution. It can also cause the heater fan to run on after the car is switched off, even when the ignition key has been removed.

I stand to be corrected.

 

[Mini Zibb]

I have an update, I finally got around to trying my spare key and everything was perfect. Heat was controllable. Is it possible for "shipping mode" as lacroupade suggested be only on one key? If not what are some other possibilities? Thanks for the help.
Tristan.

 

[markos]

I'm digging up a really old post here, but my Z4MC displayed the exact same problem as the OP's yesterday evening, during a nightmare 90 mile journey that took 3hr 15min due to terrible traffic...

No heat from the fans unless the heat dial was on absolute max: one or more notches to the left and it was just cool air only, regardless of fan speed.

Any info or updates on this guys?

Markos

 

[Ewazix]

I understood these symptoms on other BMW's and sometimes the E85/6 was down to the the final blower stage resistor 'hedgehog', which can cause a whole host f problems including parasitic drain of current and blower/heater issues. There's a 'how to' somewhere on the forum and from memory the part is hidden in the dash between the central vent and glovebox - and looked like you needed fingers like ET to get at it!

My heating was acting weird last year so I grabbed a genuine BMW new hedgehog when someone was having garage a clear out ebay and he let it go for a £1 ! I think OEM retail at £40+. I'm waiting to see how my heater behaves when I take it off SORN in the spring but can see me replacing it just-in-case.

 

[markos]

Thanks Ewazix, typically the heater is fine now, so will keep an eye in it...