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-   -   A/C fan won't turn off and now dead battery (

jaydot54 07-19-2012 08:19 AM

A/C fan won't turn off and now dead battery
2000 BMW 528i - yesterday when I turned off ignition, the A/C fan kept running. I tried turning off everything I could think of, no luck. I went ahead to take care of an errand and when I came back a few minutes later, the fan had turned off. Got back to work, turned car off and the same thing happened again. Had to get back to work and thought maybe it would turn itself off again after a few minutes... wrong! After I got off work the car was completely dead, I couldn't even manually unlock the driver-side door. I can open the trunk though for what that's worth. Any ideas on how to proceed would be greatly appreciated! Thanks...

gfsys530isrcute 08-15-2012 06:14 PM

Bad relay of some kind? Maybe in the mean time you can pull the fuse after you park it. A real pain but a temporary band aid till you diagnose it.

Pwnography 08-29-2012 07:52 PM

I like how this thread is unattended. I actually may have the solution, sorry for being late.
I also had a BMW 528i E39 1999 year model. (original buyers and parents say its 2000) The problem started when the battery was always dead, I replaced the battery; after a few weeks the problem persisted.
I found out from my local mechanic that it was a defective unit in the A/C Fan unit. Don't believe me?
Once you jump start your car and verify that your battery is working efficiently (go to a auto store and tell them to test your battery, say you have it warranted if you don't.) They will test if the battery can hold the charge. Turn your Fan to the middle setting, than to full blast. There will be no difference. The fan system will also run even when you remove the key. If these factors are faced by you, there is something wrong with the fan. The repairs on my E39 was over 400 for parts and labor.
The reason why your battery is dead on a regular basis is that the system runs even when you are not at your car. When the car is off, the alternator is not creating energy for your battery.
Good luck.

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