Hi,
You say "fan heater", if it's the fan that's not running and you've checked the fuses etc as you say then it's the fan itself. It may be corrosion on the connectors to the motor, try this before you get into replacing things. Also put a volt meter across the appropriate connectors to see if you are getting voltage when you switch the fan on, this will prove the system as far as the motor.
Cheers now
Ken Chapman, May 2007