[spaps]

After 3 and a half years in a new house, all of sudden the master bathroom fan is always ON. I replaced the 3 way switch but that didn't fix it.
I'm starting to suspect the fan or electronics (if there are any).
Is there something else (wiring for example) I should check out before buying another bathroom fan?
I measured the resistance going to the fan and found it to be short. I'm guessing this a transformer to step down the voltage to the fan or the fan motor windings itself.
I'm trying to find schematics to a bathroom fan, but not having much luck.

Any info or advice would be much appreciated.

Thanks,
S

 

[Saturday Cowboy]

more info. what kind of fan, you said something about 3 ways. I bet fan is line voltage, which suggests bad wiring, connections, switches.

 

[spaps]

There is 3 wires going to the switch. The black wire with voltage is connected to the common screw.
When the switch is OFF, the black and white wires are shorted on the switch.
When the switch is ON, the black and red wires are shorted on the switch.

In either position of the switch, the fan is always ON.

I have not looked at the fan yet.

 

[sirsparksalot]

There is 3 wires going to the switch. The black wire with voltage is connected to the common screw.
When the switch is OFF, the black and white wires are shorted on the switch.
When the switch is ON, the black and red wires are shorted on the switch.

In either position of the switch, the fan is always ON.

I have not looked at the fan yet.

If this is a 3-way, there'll be another switch (operates the fan in two locations). Did you check that switch? Do so, and post back.

From your resistance tests (hope all power was off first), it indicates that the switch is working. BTW: there's no ON/OFF on a 3-way switch. are you sure that's what you've got?

 

[gregzoll]

Who ever rewired the switch, caused a constant on to the fan. Put back in the correct switch/switches to control fan & light, and it will be fixed. Post pic's of the light and switch.

 

[spaps]

Who ever rewired the switch, caused a constant on to the fan. Put back in the correct switch/switches to control fan & light, and it will be fixed. Post pic's of the light and switch.

The switch was never rewired.

I should have mentioned in my initial post that this is my parents house. So, I'm not there to check and make measurements/troubleshoot on the fly.

 

[spaps]

If this is a 3-way, there'll be another switch (operates the fan in two locations). Did you check that switch? Do so, and post back.

From your resistance tests (hope all power was off first), it indicates that the switch is working. BTW: there's no ON/OFF on a 3-way switch. are you sure that's what you've got?

Yes, this is a 3-way switch. I didn't think there was a second switch since all other switches in the immediate area control lights. Maybe there's a switch in the basement or by the thermostat that controls that fan as well.

The power was off when I made resistance tests (I'm an electronics tech) and your right there is no ON/OFF on a 3-way switch.

I should have mentioned in my initial post that this is my parents house. It'll be a couple of days before I go back and check for another switch.

Thanks for your help,
S

 

[Jim Port]

This sounds like the double switch with a common feed, not a three way. The OP states the power is on the Common screw and there are 2 switched hot legs on the black and red.

I suspect a bad switch since the OP said nothing has been rewired.

 

[spaps]

This sounds like the double switch with a common feed, not a three way. The OP states the power is on the Common screw and there are 2 switched hot legs on the black and red.

I suspect a bad switch since the OP said nothing has been rewired.

I have already replaced the switch and got the same result with the new switch.

 

[gregzoll]

I have already replaced the switch and got the same result with the new switch.

You stated before that you did not do anything to the switch, and now you stated you replaced it. Right there is the problem. Take a picture of the junction box that the switch is in. Most likely you installed the incorrect switch for a incorrect switch that was in there before.

 

[drtbk4ever]

You know, my nephew was complaining about something similar in his 4 or 5 year old house. I cannot remember the specifics, but there is a switch on the main floor that will turn his upstairs bathroom fan on.

I don't know if it was a 3 way switch or not. We figured maybe it was some sort of interlock situation. Strange very strange.

Maybe the same guy wired your parent's house?

 

[gregzoll]

You know, my nephew was complaining about something similar in his 4 or 5 year old house. I cannot remember the specifics, but there is a switch on the main floor that will turn his upstairs bathroom fan on.

I don't know if it was a 3 way switch or not. We figured maybe it was some sort of interlock situation. Strange very strange.

Maybe the same guy wired your parent's house?

Multi-wire branch circuit. Only happens when people make changes to a system that worked before, but now things are messed up and the person does not know why. Murphy's law states that once you touch something, it is guaranteed to be screwed up and cause you headaches.

 

[Jim Port]

I have already replaced the switch and got the same result with the new switch.

Switch the position of the 2 blacks on the switch.

 

[drtbk4ever]

I have already replaced the switch and got the same result with the new switch.

I think he is saying the problem existed with the old switch too.

 

[gregzoll]

I think he is saying the problem existed with the old switch too.

Because the first switch was never installed correctly.

 

[williswires]

After 3 and a half years in a new house, all of sudden the master bathroom fan is always ON.

...usually means SOMETHING has changed that your parents are forgetting to tell you...new light, receptacle, or other device changed or installed...

I replaced the 3 way switch but that didn't fix it.

Does this fan have a light too, or is it just a fan?

Are you sure a set of 3-way switches was installed originally? Can you find a reason WHY 3-ways would be installed to control that bath fan?

Is this fan wired so the light(s) and/or fan come on whenever someone turns the regular bathroom light on, OR only by using the switch you are dealing with?

As gregzoll mentioned, pics are always helpful!

 

[spaps]

Multi-wire branch circuit. Only happens when people make changes to a system that worked before, but now things are messed up and the person does not know why. Murphy's law states that once you touch something, it is guaranteed to be screwed up and cause you headaches.

All of a sudden the fan in the bathroom is always ON. I replaced the 3-way switch with the same type of switch and the situation is still the same. I put the original switch back.
The circuit was not touched before the fan was noticed to be always ON.

I'm going to have to go back and see if another switch in the basement or by the thermostat was turned on by accident.

So, right now, I suspect another switch or the fan itself maybe defective. I'll send an update by Thursday after I have another look.

 

[Timster]

If you cannot find that other switch, and your parents never use it, then perhaps cap the travelers in the switch box in the bathroom, and wire up with a normal non-3way switch; just the hot and fan leg connected to regular switch, with the 2 travelers capped and tucked back in box... just a thought.

oops, edit: Disregard the above since, if it is a 3 way switch box, then there is only a light or hot leg in the box, not both...

 

[frenchelectrican]

If I recall it correct there are few spots in Canada when you use the exhaust fan(s) few will be hook up to the make up air unit or air exchange unit that why they were interconnected so any one of the exhaust fan kick on the air make up unit or exchange unit kick on to provide fresh air.

So therefore if you hit any switches in any fans they will have a extra conductor going to the air make up or exchange unit to run the same time.

I have heard it before and I know I did ran into once in brand new home in Wisconsin when someone make this house super airtight so have to use the air exchange/make up unit.

Merci.
Marc