I have a 2003 Mini and lately at times a fan is staying on after the engine is turned off and draining my battery. Because it doesn't always do this, the mechanic can't figure out what is happening. Does anyone else have a common problem?

 

there are only a few causes ,
car overheating ? low on coolant bad stat ect may cause the fan to run after trying to cool it off


bad relay , bad connections on harness , bad thermostat switch

I've seen the relays stick intermittantly
I've seen the connectors get corroded