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06-24-2020, 07:04 AM #11
Folks, the problem has already been deduced by process of elimination. Each new motor making the same noise. Noise gone when on full. This, as the first reply to the original post speculated, is the result of the speed control PWM scheme. Won't matter if they send a new controller if the scheme is the same. Customer service will never be able to implement a change. The best they can do is send parts. Only the design team can make a change, and it is one where the PWM frequency needs to be shifted more out of the audible range. This is actually an incredibly common problem wherever PWM is used to control fans whether home computer, vent fans, refrigeration fans, and on and on. ALL of these makers work under if 10-15% of consumers are negatively affected, that's acceptable. You have to keep that very real, mass production, economic consideration in mind because the squeaky wheel doesn't get the grease in these scenarios...
I deal with this problem all the time in my plants, and it can be fixed when you have the influence and path to those that can. However, that is practically Impossible in the RV industry for a consumer. Best thing you can do is try a different brand - it appears this postal may have crossed fan brands too.
I seriously wish you good luck in a resolution as when I was younger I would detect high frequency very, very readily.
Fortunately/unfortunately, it's dulled as I age.Last edited by geotex1; 06-24-2020 at 07:29 AM.
Rob & Nikki + Cloverfield
2020 Grand Design Solitude S-Class 3350RL
2015 RAM 3500 Longhorn Laramie Crew Cab, Long Bed, 4x4 Dually Cummins/AISIN
Mountains of Pennsylvania
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06-24-2020, 10:01 AM #12Resistance is Not Futile, It's Voltage Divided by Current.
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06-24-2020, 10:23 AM #13
Not weird. Dirt build up can cause a change in harmonics too, or cause imbalance in a wide tolerance assembly so the shaft rubs. Cleaning out the dust and degreasing blades shoukd be standard maintenance. This was just not the OP's issue since he's working with several new replacements.
Rob & Nikki + Cloverfield
2020 Grand Design Solitude S-Class 3350RL
2015 RAM 3500 Longhorn Laramie Crew Cab, Long Bed, 4x4 Dually Cummins/AISIN
Mountains of Pennsylvania
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06-24-2020, 10:44 AM #14
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My Maxxair fan has made the high pitch squeal since it was brand new. I can't hear it at all but my wife sure can. She lets me know about it every time that I turn it on. I had the dealer look at it but they could not hear it. Go figure. We only run it to get cooking fumes out of the fifth wheel. If I can figure out how to use the same control and power wires I might swap it for a Fan-Tastic fan in the future.
Kevin and Jennifer
2016 RAM 3500 Laramie Mega Cab CTD Aisin 4x4 SRW
2019 Reflection 28BH (Built 2/2019)
- 78" Theater Seat, Second AC, Dual Pane Windows
- Sailun 235/85 R16 Tires
Blue Ox Super Ride BXR7200 with a Demco Factory Prep Bracket 6099
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06-30-2020, 08:17 AM #15
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To go further I hooked the power source to a dc power supply, set the power supply at the recommended voltage for each speed. Absolutely no noise. at any speed plugged the motor back into RV and noise is back. Rediculous
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06-30-2020, 09:14 AM #16
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I had 2 of them in my last camper, both installed new by a local shop. Both made the sound, but I just looked up, shrugged and didn't find a way to care about it that much. They move air, like for real.... and draw in cool evening air that the little OEM fan would not do. I love the big fans and will take the somewhat digital sound over the hot air any day. I think that some folks are more sensitive to certain sound frequencies compered to others. I am obviously not that sensitive to this frequency beyond observing it and ignoring it.
My suspicion is that those who have more sensitive hearing that find the frequency to be overwhelming are going to be unhappy with this style of fan no matter how many parts are swapped. Just as we all see better/worse, see colors differently, smell differently... I really think we hear differently.2020.5 Reflection 311BHS Dual AC, 2019 Ram 2500 Bighorn Level 2, 3.73 / 392 Hemi 14,404.34 lb towing and 3,004.34 payload, 2019 F-150 King Ranch 3.5EB CC/LB, 2016 Cherokee Trailhawk, 2014 Wrangler Willys Edition, 2019 Iron Bull 14K 22' Equipment Trailer, 2019 Quality Trailers 7K 18' Utility Trailer
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07-05-2020, 06:25 PM #17
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Hello geotex. I am tired of working on this I have exhausted over 80 hours trying to figure this out. Tonight I brought the whole assembly into the shop. Hook the assembly up to a power supply and the noise is still there. I hook up the motor by itself and it is gone. So basically in my mind the circuit board that controls everything is the culprit. What baffles me is they sent me a new one and it does the same thing. The motor speed is controlled by 4 different voltage readings for each of the 4 speeds.
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07-05-2020, 07:15 PM #18
Yes, the board is what it causing your issue. It's the PWM that used to control the speed increments. Now that you have testing two boards, you have essentially confirmed this is the normal operation. Unfortunately, your hearing is sensitive to the frequency used in that normal operation. They would need to redesign the control board so the frequency is pushed further out of audible range. Your best bet it to try the other brand of fan unless you have friend that is into electronics and could make up something custom. If you're ok experimenting, why not get a rheostat and put that between motor and power and control speed that way and see if you have success. If you don't want to spend uncertain cash, you could use some resistors to bring the voltage down and listen to what the motor sounds like. I bet you'll find the motor is fine throttled when not done via PWM. Then the question will be if a not so hi-tech control will work for you. You can definitely get a wall mount rheostat.
Rob & Nikki + Cloverfield
2020 Grand Design Solitude S-Class 3350RL
2015 RAM 3500 Longhorn Laramie Crew Cab, Long Bed, 4x4 Dually Cummins/AISIN
Mountains of Pennsylvania
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