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Extractor fan not spinning, has power

Discussion in 'Electrics UK' started by LondonRoss, 29 Mar 2020.

  1. LondonRoss

    LondonRoss

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    Hi all,

    Vent Axia Solo Plus HT (Model 427479) power but not working

    I have a Vent Axia ceiling mounted extractor fan in an internal bathroom which has not been operating for the past few months. The unit is connected to the light switch and seems to be connected to the power as a blue LED light on the extractor fan turns on when the light switch is on. The fan itself, however, does not spin even when the LED is lit.

    I have removed the cover and there are no obvious obstructions to the fan - it spins quite freely by hand. I have also reduced the Humidity screw adjuster to the lowest level (anti-clockwise) just in case it wasn't turning on due to any lack of humidity when I was testing. This made no difference. Does anyone know what might be causing the unit to be inoperable? Perhaps the motor is blown? Or the humidity detector frazzled? Is it something to do with the switch on the top right of the picture (does this switch check that the cover is on?)

    Extractor fan.jpg

    I have found a replacement unit online for £80 or so which I am happy to purchase (https://www.ebay.co.uk/i/1507562685...a0IR76uCdHto3Wqj5trNy4h4Ki8e_vzMaArv6EALw_wcB). Will this be easy enough to fit without expertise?

    Thanks for any tips and advice.

    All the best,

    Tom
     
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  3. JohnD

    JohnD

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    IMO humidity sensors are not very reliable. You might consider a timed fan next time.

    Does the light switch have any effect on the fan? If so, you should find one black or blue wire connecting to the fan, and two brown or red ones.

    The fan in your pic blows the steam out of a vent in the bottom left of the pic, presumably there is a hose above the ceiling. This is not a common layout, have a look in the ceiling space. If there is a 100mm flexible hose up there, it will probably attach to other fans, but you need to know how much room you have. Loft access will make it easier.s
     
  4. endecotp

    endecotp

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    Does it make any sort of buzzing or humming noise when it should be running, or is it completely silent?
     
  5. endecotp

    endecotp

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    I see two little plastic pegs to the right of that switch; is that a hole where an in-off pull-cord could go? (Often fans have numerous slightly different models; maybe there is a version of your fan with a pull cord.). Or it could be a cover-off switch as you suggest. In any case, it’s easy to check, just put the cover back on!

    Do you have a multimeter?
     
  6. muffking

    muffking

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    Yes that switch on the top right is probably a saftey switch to ensure the cover is on. You may need to hhold this in while testing.
    Based on the photo you should be able to check for 230v between Neutral to Live (blue sleeve to brown wire) and also Neutral to switched live (blue sleeved to brown sleeved), both with the light on. If you have power to both then you can hold that switch in and adjust the humidistat in both directions. If it still doesn't come on then the motor is goosed.
     
  7. LondonRoss

    LondonRoss

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    Thanks John D - The only effect of the light switch is that it makes the LED light on the extractor fan turn on. The extractor makes no noise beyond this, however, and the fan itself does not spin. There is indeed a 100mm hose in the ceiling cavity that leads to an external outlet 3-4m away. I live in a flat with no access to the ceiling cavity, however, so not much I can do with that. Surely the problem must be with the ventilation unit itself no?

    Endecotp - I think you're right on the plastic pegs and the switch. It looks like it allows for a thin pull-cord to be run through. For my set up it was arranged to turn on and off via the main light - so I take it this switch is disconnected.

    I don't have a multimeter but can get one tomorrow if I know what to check for. I wonder if it is the humidity meter that is busted and I might be able to bypass it. I've attached photos of the circuit board in case you might be able to advise on what I should be testing with the multi-meter (not neon screwdriver, as I've learnt from other posts!!).

    Extractor circuitry 1.jpg Extractor circuitry 2.jpg

    Cheers! Tom
     
  8. JohnD

    JohnD

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    there is a faint chance that the adjustment pots of RH and Time Delay have failed, so you could try wiggling them and setting to min and max respectively.

    I think I can see the red and black wires that go to the fan motor. If you can identify the brown and blue (or red and black) incoming wires that beome live when the light is turned on, you could bypass the control circuits and just have the light switch turn it on. If you have energy-saving or LED lamps, the cost in electricity will be trivial, even if you leave it running all day.

    Linking will tell you if it's the motor failed, or the control circuit (IMO more probable).

    It would be useful, if you can take the whole fan down, to see the size of the hole, and the position of the hose. Most likely a similar fan from the same maker will have the same dimensions, but as I said, I wouldn't bother with a humidstat, I'd go straight to a timer model.
     
  9. muffking

    muffking

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    Are you sure that's a good idea?
     
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  11. JohnD

    JohnD

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    what? the linking?

    why not?
     
  12. muffking

    muffking

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    Yes. Because if it's a DC motor and/or low voltage then I would be standing well back.
     
  13. endecotp

    endecotp

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    I don’t see enough components there for it to be anything other than a mains motor; I think the blue box is just a relay. But better safe than sorry in any case.

    It may be possible to hear the relay operating.
     
  14. endecotp

    endecotp

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    There are of course lots of things you could check with a meter; one thing I’ll just note now because I’ve looked it up is that the power pins to the LMC68641N quad op-amp are the middle pins on each side; you should get a modest DC voltage (less than 16V) across them whenever the perm live is on.

    You obviously need to take great care when poking around in something like this with power connected. Don’t do it without someone nearby.
     
  15. flameport

    flameport

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    With power off, use the multimeter on continuity/low ohms setting and measure across the two wires that go to the motor.
    If there is a low reading, motor probably ok. If it's open circuit, then the motor has failed (probably the thermal cutout inside).
     
  16. LondonRoss

    LondonRoss

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    Cheers guys. It sounds like whatever it is, it is pretty buggered beyond what I might reasonably fix! I've ordered a new timer only version from amazon so fingers crossed that does the job. It was over 10 years old afterall...

    Thanks for all your help!
     
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