When the fan is working it causes a pressure plate to close which complete a circuit which in turn causes the spark generator to produce the spark which you can hear. If you cannot hear the clicking of the spark ( this will be continuous until the pilot lights )it could be the pressure plate or the spark generator or that the pipes leading from your fan to the presure plate are blocked. Check by using a circuit tester. If you hear the spark but the pilot light does not come on it could be that the pilot light pipe is blocked or the spark is not close enough and needs adjusting.
Geoff, February 2007
