Suggestions 1:
Is the fan supposed to stop with the door open?
Is the door open or closed?
Is the fan free to spin?
Are you getting power to the fan when it should be on?
Is the fan open circuit? You may need to do a resistance check. Assuming a 240V, 10 to 25Watt fan motor, expect SOMETHING like 6000-1000 ohms (or thereabouts) across the winding of a disconnected fan. Certainly open circuit = knackered fan.
Suggestion 2:
Mention the make and model - we ain't psychic (despite what my kids think)
Acp
August 2017