My bathroom fan/light timer is haunted, turns on by itself!

10 years ago

I need some help/advice, I'm not getting any sleep!

The past two nights we were woken up by the bathroom fan/light timer starting up. We have one of the timer switches with the set buttons and an off button. It can't turn on unless you push a button. Or so we thought.

It's really creepy. You hear the fan kick on in the middle if the night, roll over, and the bathroom is all lit up! The first night we just turned it off, I figured DH didn't remember turning it on. Last night I kept track, and it was on for 60 minutes, the longest time you can pick. Different start times both nights, only one episode per night and none during the day that we are aware of.

What would cause this all of a sudden? We are having some kitchen work done, but the wiring has been done for weeks and nothing was altered Friday.

Featured Answer

randy427

10 years ago

Perhaps the ON button is not popping fully back up after you release it and the switch makes up its own 'mind' as to when there's enough contact to activate.
Instead of relying on just the timer to turn it off, if that's what you normally do, perhaps pushing the OFF button would unstick the mechanism.
Or maybe it's gremlins.

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Comments (10)

ionized_gw
10 years ago
Some bathroom fans or switches have humidity sensors. If you have one, It could be malfunctioning. IIRC, they typically operate on some combination of humidity rate change and RH level.
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williamsem
Original Author
10 years ago
Ok, great theories! Will try the off button tonight. Don't think it has a sensor, but will dig out the manuals tomorrow. Hoping for a whole night of sleep tonight.
abbey_cny
10 years ago
If the power goes off in my house, when it goes back on the bathroom fan will be running even though no one has turned it on. So could there be some kind of slight power fluctuation going on?
williamsem
Original Author
10 years ago
I can't imagine we are having power fluctuations in the middle of the night, but not during the day? From what we've seen in this house though, I wouldn't rule it out.

Two nights without incident so far. I made a point of turning it on right before bed and using the off button. Will try not using it one night this week to see if it happens again. If it's the switch, at least that's an easy fix.

Will post back with an update. I hate finding stuff online that's exactly what I need but no resolution at the end!
williamsem
Original Author
10 years ago
UPDATE
So today DH sends me a bunch of text messages chronicling his fan experience this evening. Between 5 and 9 tonight he says the fan came on by itself 30 times. I was at work, so I can't verify.

We were having thunderstorms in the area all afternoon/evening. Does this provide any insight into a cause? My contractor still has some odds and ends to finish here, so if something needs checking I do have a qualified person to check.
randy427
10 years ago
I think I'd shop for another switch.
williamsem
Original Author
10 years ago
If this is most likely a switch issue I'd be happy to swap it out. The fan and light operate together, so easy for me to do.

If there's more than a very remote risk of the issue being with the circuit, panel box, power supply, or interference with other lines nearby, I'd rather rule those out for peace of mind. If those aren't even possibilities for this issue, I won't waste GCs time.

It's just so odd it started all if a sudden. And coincidentally during an extensive kitchen remodel. Just trying to be safe.
toxcrusadr
10 years ago
Is it a digital timer or a rotary mechanical timer knob? I guess it doesn't matter, either way it seems defective and should be replaced. If it does that, who knows what else it's capable of. It might try launching the missiles next.
Mitchell Campion
3 years ago
I have experienced this issue (fan randomly coming on in the night) and believe I have found both the cause and the solution and would like to share it with you.

Firstly this is to do with an inline fan system where the fan draws air out of a shower light assembly and then pushes it out through an external vent.

The problem is moisture getting into fan timer electronics which causes the circuit to switch the fan on, sometimes with irregular pulsating speed. The solution will be to remove the timer circuit board and dry it out. However, you will need to make sure it doesn't happen all over again. There are two things I did in an attempt to make sure the problem didn't reoccur:

1. The wires from the fan (the fan is in the moist air flowing along the pipe) connect to the timer circuit through a channel in the fan housing. Air can also travel along the wire channel bringing moist air with it where it condenses. Use a sealant to block the channel before replacing the timer circuit board.

2. The air will be forced down the wire channel if the outside vent becomes blocked - it will try every route to escape. Keep the outside vent clear. In my case it was blocked with lint and fluff.

Hope this helps

My bathroom fan/light timer is haunted, turns on by itself!

randy427

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ionized_gw

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My bathroom fan/light timer is haunted, turns on by itself!

randy427

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ionized_gw

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