Bathroom extractor fan doesn't turn off - any ideas? Ask questions and find answers to many subjects relating to electrics and electrical work

[corum_uk]

In the ceiling is a small extractor fan with a halogen light in the centre. In the loft space two white wires come off of the unit and enter a small white box. Two wires (red and brown I think) exit the box unit.

At the switch side, the light and fan have separate switches on the wall. The light turns on and off fine but the fan just keeps running and I have to trip the fuse box switch to shut it off.

I can't see a separate permanent iive going to the unit so am a bit mystified but would like it to just switch on and off using the wall switch.

[url]https://www.dropbox.com/s/ikd0adberusb1qo/fan.jpg?dl=0[/url]

Any tips appreciated.

[ericmark]

Normally fans have some form of run on normally set to about 15 minutes. Also humidity sensors are popular. I did find with my fathers shower it took a long time before the fan turned off clearly the room was too damp.

[corum_uk]

On closer inspection (and looking at other units available online) the fan is separate to the light and must be situated at some point further along the duct and wired separately. I'll have to get back up in the loft and try and isolate it for a closer look.

[corum_uk]

Ok so...

Turned off the upstairs light circuit from the fusebox.
Found the fan!
Tested with a multimeter to ensure no power was on.
It has two red and two black wires only, although there were two other 'internal' black wires leading from the live terminal to somewhere inside the fan. Not sure whether disconnecting one of these would disable the timer but..
The timer dial was set at about 1/4 turn, so i dialled it right back to zero and tested....
It turned off after about three minutes.
So hopefully that's fixed it, although there is clearly something faulty in the fan for it to have been running non stop before (it never used too).

Photo of fan wiring attached.

[url]https://www.dropbox.com/s/guthrh16z4n637v/fan%20wiring.jpg?dl=0[/url]