my motor fan

assuming you mean the cooling fan under the hood,check the coolant level. check when cold....

That's pretty much normal operation .. The *radiator cooling fan* turns on as directed by engine temperature .. When engine is turned off - engine temperature actually rises due to 'heat soak' - then when key is cycled back on - cooling fans also turn on. As long as the engine temperature is normal as indicated by the temperature gauge - no worries. (The cooling fans also turn on when air conditioning is operating)