E85 Heater Stuck On Hot!

M

malc24

Member
Hi Guys,
My 2007 2.5i Z4 Sport's heater (with auto air con) stays hot (max hot) regardless of whether the temperature dial is set to cold or any other position.
Before this happened the heater fan would cut out from time to time but come back on of its own accord.
I've tried wiggling the wires at the back of the controls to no avail, and the connections all seem tight. :headbang:
I'm suspecting that the heater control / contol module (containing three control knobs and various buttons) is faulty. There is one for sale on ebay which looks the same -
http://www.ebay.co.uk/itm/BMW-Z4-06-09-HEATER-CONTROLLER-A-C-0000308492/361766174970?_trksid=p2047675.c100005.m1851&_trkparms=aid%3D222007%26algo%3DSIC.MBE%26ao%3D2%26asc%3D20140122125356%26meid%3D65da4526afd947728efaa760d9347d97%26pid%3D100005%26rk%3D1%26rkt%3D4%26sd%3D332156859830[/url]

But I'm not sure whether the fault lies with this component. :dizzy:
If it does, the centre dash vent and radio have to come out to be able to fit it apparently.
Any advice from someone who has heard of / experienced the same problem ( and got it fixed!) would be much appreciated, as would advice on how to get the centre vent and radio out and whether a replacement heater control / module needs to be coded by a dealer or specialist to suit the car. The following BMW info on the heating system vaguely suggests it may need coding -
http://www.bmwclub.lv/files/07_E85_Heating__and__Air_Cond.pdf
 
Thanks very much for your advice but I think all the resistor does is control the fan speed and the fan is actiually working OK on all speeds.

Has anyone had the heater stuck on hot regardless of temperature setting?
 
No idea how it works on these cars, but on previous cars I've had that have had a similar fault there is a dedicated heater valve which directs or diverts hot engine coolant into the heat exchanger unit. So it might be the controller that tells the valve to move or the valve itself, if thats how it works :rofl:
 
Hi Marc-j, Thanks very much for your reply. It could be the valve as you say (its got one somewhere under the dash). But then again it could be the control module.

I've now noticed that the air is only coming out of the vents at the top of the dash regardless of the chosen settings.

Have booked the car in with Martin Wright (a local specialist) for diagnosis. He said that the control module has gone into default mode -apparently in this mode the system has sensed a defect and so blows air at the windscreen only to allow demisting (seems sensible).

He needs to check the car to find the reason.

I'll post an update when its been checked out and / or fixed.
 
You sure it's not just in transport mode? If so it could be a fix with BMW coding. Maybe worth clarifying before parts start getting swapped at great expense.

see http://www.z4-forum.com/forum/viewtopic.php?t=46716
 
Hi Guys, As a belated update and if it helps anyone else - I fixed the heater issue with a heater control panel from Ebay (comes complete with all the knobs and buttons). This turned out to be easy to fit after removal of the centre air vents which was the only tricky bit due to the 'invisible' spring clips inside the top of it.

The vents have to come out to get the radio /CD player out in order to access the two fixing screws on the top of the heater control panel that fasten it to the dash (along with side clips).

The heater control panel can then be squeezed out of the aperture below it after removal of a small cover between the centre console and the dashboard (the cover which has the audio input socket in it).

Great to see all the forum members and cars at Z Fest. Such a fanatastic day out, and I got my roof motor relocated whilst there by Mike (thanks mate!), so even more worthwhile. :thumbsup:
 
Stick it to min and max a few times with 'auto' off. Mine was stuck on ice cold after it was regassed and this fixed it for me...
 
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