Maxx Air Fan - Any last suggestions to fix high frequency noise before I give up?

[namtaru]

It's not the bearings. It's not the commutator. It's not the carbon brushes.

It's the high frequency noise that comes from PWM of the electronics that is driving me absolutely crazy. I have extremely sensitive hearing to high pitch noises, and they give me headaches.

Has anyone modified the fan at all to completely remove the controller and other electronics, and just have it be on or off at a single speed? Or anything at all before I give up and just accept the fact I have a fanless vent on the roof?


2023 324MBS

 

[Dutchman2]

It's not the bearings. It's not the commutator. It's not the carbon brushes.

It's the high frequency noise that comes from PWM of the electronics that is driving me absolutely crazy. I have extremely sensitive hearing to high pitch noises, and they give me headaches.

Has anyone modified the fan at all to completely remove the controller and other electronics, and just have it be on or off at a single speed? Or anything at all before I give up and just accept the fact I have a fanless vent on the roof?


2023 324MBS

Is this happening at all speed ranges? Not sure the fan runs on PWM power supply? Might look into tightening the hold down bolts to change the housings natural frequency. My other thought is to compare another unit with the same max air fan and see if you hear the same high frequency noise.

Dutchman2

 

[LivingLawlessAdventures]

I have two and they make the same noise - it actually helps me to know when the fans/vents were accidently left open.
That being said, I think that's just how they sound.

 

[Casa_Woody]

Same issue. I just turn the music up a little louder.

 

[namtaru]

I finally fixed it....

I reached out to AirXcel, and while I give the company big props for being very responsive, and sending me replacement parts, nothing they sent me fixed the issue.

The noise was coming from the motor, but it was only after I tried almost everything that I realized it was being caused by the circuit board using PWM to control the speed of the fan. After seeing another post on the forums, I hooked the motor directly up to 12v bypassing the circuit board, and BAM, no high pitch noise.

I ordered a $7 PWM fan controller from Amazon, bypassed the OEM circuit board, and instantly.... any speed I wanted, with no high pitch noise. There was a small hole on one side of the shroud that I made bigger and put the knob through that hole.
I kept the original circuit board in there so I could still open the hood from the wall, and luckily I'm a tall person so I can reach the new control knob where I installed it in the fan shroud on the ceiling, but I'm SO relieved to finally be able to run the fan at low settings without that high pitch squealing coming from the damn thing...

https://www.amazon.com/dp/B09P6CMRC9