Mercedez 2008 two door smart car 98000 miles automatic
i have a 2008 two door smart car i have battery unplugged until i need it when i hook it up a fan is running i turn car on it the fan still goes when i turn car off it runs until battery is dead dont know what fan it is i check the relay and all is good the fans still running
I'll say right off the bat I am not familiar with that vehicle so the following are generic suggestions. Others here (maybe @jack62) might have more detailed and specific information for you.
If it's not the interior HVAC fan running, which should be self-evident inside the car, it is probably a radiator cooling fan.
Cooling fans frequently are set up to run for a short period of time after the engine is turned off if the coolant temperature is high. You need to check a wiring diagram for the car to see how the cooling fan is controlled. Does it have its own temperature sensor? Is its engine-off run time controlled by a time-delay relay or by a computer module? Once you have identified the control mechanism you need to trace out the circuit and test the components. If the fan is computer-controlled (likely) you'd need a high-level bidirectional scan tool to diagnose the problem.
could it be a bad thermostat
its a good thermostat
would it be a radiator fan or something