The aux fan (aircondition) keeps running even after I pulled the ignition key out on my 85 380sel. I only realised after trying to start the car and the battery was flat.
I had to replaced the battery but the fan immediately start to run again when I connected the battery cable.
I had to disconnect the wire to the aux fan to make it stop.
Now I can't use the aircon because the car might overheat without the aux fan connected.

I may be wrong - especially since it continues after you pull the key out but by first thought is a bad switch that turns the fan on. If it is running in high speed I would suspect the a/c pressure switch. If it is running in low speed I would suspect the engine temp. switch. Use a volt meter to check these particular switches out.

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Jim

i agree about the bad switches, and your doubt since it occurs when the key is out. It might be a combination of the ignition switch and a bad switch since there should be no power to the fan with the ignition off.

Does this model have a 'run-hot' function whereby the aux fan keeps running at very high engine temp, even after the car has been switched off ? maybe that switch is the culprit ....

my 0.02's worth
L