1991 5 series E39 BMW heater controls cooling fan

[OmanYorkie]

The heater / a.c. control unit cooling fan is running all the time and drains the battery eventually. How can this be stopped. A replacement heater / ac control unit is around £450.00 which is a lot just for a faulty cooling fan ?

[Hymie]

My advice would be to check out BMW forums on the web – you might find it a common problem with a simple fix.

In the meantime – if leaving the car un-driven for an extended period, identify and pull the fuse supplying the A/C fan.

[OmanYorkie]

Thanx Hymie. I will see if I can get hold of a wiring diagram to identify the fuse, but fear this fuse may control the entire panel and not just the small fan.

[AlBags]

You mean the main cooling fan(s) on the rads?
It will likely have it's own fuse ... and quite a large one.
If there is a permanent live to the motor via the fuse, then the module/motor could be faulty and needs replacement.

[Hymie]

The fan controller will almost certainly be permanently live. A fault has developed such that the fan is always on. Once you obtain the wiring diagram you could consider putting a switch in series with the fan/controller – or alternatively, power the fan/controller off +V switched via the ignition. But you have to ensure that it had the capability to power the fan/controller plus whatever it is normally powering.

[OmanYorkie]

Albags, thanx for your response. It is not the rad fan, but a small fan in the in-car a/c / heater control panel to keep the electronics cool

[Toureman]

This is the place to go to............Ask the experts!

http://www.bimmerforu...ex.php?do=view&page=3

[AlBags]

OK ..
I have seen these before ..
I think you should use the forums as suggested .. you will have to replace something for sure.