Bathroom fan starting to make annoying low frequency hum

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Old 03-13-19, 10:42 AM
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Bathroom fan starting to make annoying low frequency hum

We had a Panasonic vent fan put in our bathroom during a remodel about a year ago. It runs very often as the bathroom is used often and for about the first year was actually incredibly quiet- basically the woosh of air moving through is all you really could hear. This past week or so I have noticed it starting to emit a very low frequency humming noise on top of it's normal sound. It's not super loud, but the low frequency makes it very "hearable" and super annoying (to me at least). I would hate to have to open up the ceiling- are there any tips or tricks less intrusive measures I can look into to fix this? My first thought is to suck off any dust build up on the fan blades thinking maybe there is some asymmetrical accumulation that might be causing a balance problem..

(it is a Panasonic FV-11VQC5 WhisperSense 110 CFM)
 
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Old 03-13-19, 02:44 PM
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Remove the cover and give it a good cleaning. Maybe it's a dust buildup causing an imbalance. If that doesn't work run the fan with the cover off and see if pressing on parts of the metal housing will quiet the sound. Adding and extra mounting screw or some spray foam on the outside can quiet "oil canning" of the sheet metal housing box. And as a last resort replace the motor. Maybe the motor's bearings/bushings are wearing out.
 
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Old 03-13-19, 04:07 PM
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As Dane mentioned... try pressing parts of the case to see if it stops.
I've installed a lot of those fans. I've never had to change a motor yet and they've always been quiet.
 
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Old 03-13-19, 04:33 PM
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Well it was all the dust- there was so much caked in between the veins of the fan they sounded almost like solid things as they clunked down through the vacuum hose! Not only is the low frequency hum gone, but airflow is way up. I think since it accumulated over a year I never noticed!! The fan does move an amazing amount of air very quietly- thanks folks!
 
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Old 03-13-19, 04:46 PM
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Ahhhh...... dust caked in one year.
I'm imagining a female with hair spray. Does it every time.
 
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