I have a MaxxAir vent that did this exact thing off and on for nearly
I called them and they gave me a new motor. I installed it a couple
weeks ago but haven't been camping to give it a good test yet.
It seems like it might be better.
The motor cannot be lubed. It has no oil holes and can't even be easily
See my post here. MaxxAir above and beyond good service!
At this point I'm not completely sure if the howling is from the motor or
if it's a wind harmonic from the fan blade itself.
It seemed OK when I briefly tested it the other day.
MaxxAir has awesome customer service. Give them a call and ask for
engineer Gary T. (I had his last name but can't find my note!)
MaxxAir was bought by another company but Gary moved to the
new company so he knows his stuff and is a super nice guy to talk to.
NOTE- changing the motor was easy, getting the fan blade off the old motor
was not. I'm speaking as a guy with 37 years industrial maintenance
under my belt. I've pulled/replaced literally hundreds of gears, sprokets,
bearings and fan blades over my career. This little plastic fan blade was a
pain to get off the shaft. You might ask Gary if he'll ship you a new blade
with the motor. It's plastic and can't be that expensive on their end.
Now if you were buying it yourself- who knows what they'd charge.
I think he'll give you one if you ask.