Hi Bren Having looked at the schmatics for the 150te (which I assume you have) the fan is connected directly accross the mains input so I would expect it to come on as soon as the power is connected. so you may have a sticking fan. To test get a wooded stick (wooded spoon?) take panel off to get access to fan, plug in and if fan is not turning give the blade a tap to turn it to get it started. If it starts turning then, then it is prob sticking. You could (after unpluging!) try a spray of oil onto the bearing at the centre of fan if you can see it. Try not to use WD40 as it will cause the bearing to swell and will stick more in future. Might be worth looking for a similar size fan to replace it in future (not will need to be a 240vAC fan)