The fan on my Hy VFD is super noisy. It seems like a common problem. Did anyone replace it with a quieter one? If so, what 50mm 24V fan do you recommend?

1 Like

It’s been bugging me too, and I plan to replace that awful fan, but currently it’s too far down my priority list. Here’s the video that got me thinking about swapping the fan (but it’s not a 5 min thing)

I’ll be very interested to hear about it you do this upgrade !

Isn`t there a temperature setting you can change on the VFD so that the fan doesn’t run below a certain threshold? The fan on my VFD doesn’t start until its well into a job and by that time noise isn’t really a problem.

Disclaimer – my VFD is not a HUANYANG, its one of the other Chinese knock-offs but it does at least look identical…

Nope, at least not on mine (I just checked the manual to be sure). The darn fan starts as soon as the VFD is turned on. I may have a botched unit where they failed to mount the thermistor, or maybe they’re all like that.

I use several GE VFDs and they all come on only when needed, and they are quiet. I’ve another one that is a Chinese brand on my dust collector and it is always on and it is noisy too. But not easy to replace

I’ve ordered these fans: I only needed one, but for 8 bucks they sell you 5 :astonished: The reviews seem OK, so finger crossed.

I would’ve gone with Noctuna, or a similar well-known silent fan, but since it requires 24v, a PC type fan won’t work.

Based on a youtube video of a guy adding a thermistor to his, the VFD fan plug is easy to reach. We’ll see. I’ll update this post with the results.

If this won’t work, I might either go with the thermistor alternative or replace the fan with a 120mm version. Seems like the VFD will accept that on its back, but I’ll need to cut it out.

It seems all HY VFDs are like this. Lots of other people complain about it. Not sure though why I can’t seem to find anyone that replaced the fan… Seems like a very easy drop-in solution.

Okay, so the fans I’ve ordered were the wrong size. However I also’ve ordered a temperature triggered switch, like the one in Julian’s YouTube video link. I’ve installed it, with the original fan, and all is well and quiet now.

Easy installation - 20 mins max.

1 Like

Interesting, can you share details/link about that temperature triggered switch and how you installed it?
How long does it take for the VFD to reach the temperature where it kicks in ?

After spending hours this week-end with this horrible fan noise in my ears, I’ll certainly take a second look at this upgrade.

I would hope that the temp sensor is mounted directly on to the largest chip in the case, not just loose inside. Sure way to burn it up…

can you share details/link about that temperature triggered switch and how you installed it?

Julien, I followed the video you’ve posted:

This is the switch:
and the tape used to secure it to the heat sink:

There are 12 screws to remove to access the fan’s connection, then cut one of the fan’s wires, solder the switch wires in series with the fan, isolate the wires with shrink tubbing, stick the switch to the back of the heat sink, reassemble. Done.

Just tested the switch with a heat gun and it works.


Thanks. For the switch, did you take the 40 degrees version or some other value?
If you have the opportunity to do long jobs, I’ll be interested to hear about how long it takes for the heat sink to reach that temperature and trigger the fan.
I wonder if wiring a thermistor would be easy enough, to have a more gradual ramp of fan speed. And I will also hunt for a quieter fan of the same voltage/diameter, maybe this would be a good compromise.

Based on the designs I did in my EE career I’d opt for a variable speed fan and the sensor on the component that generate the most heat.

It takes surprisingly little air to remove the majority of heat. It shocked me and I ran my own experiments that confirmed it on my designs. So a slow speed fan will make little noise and remove a lot of heat and them go to higher speed as the demand dictates.


I did use the 40deg switch. Please update if you find a quitter fan. The challenge is that it’s a 12V.

The VFD has a massive heat sink on the back. Mine never even got warm. As a note, my spindle is a 800W version, while the VFD is 1500W. Maybe that makes a difference.

I may invest 10 bucks to try one of those (or similar)

I was thinking about a similar set-up but decided against it for two reasons: (1) KISS (keep it simple [talking a bout me] stupid), and (2) not wanting anything outside the VFD (there’s no empty space in the case).

Please let us know how it goes. Does your VFD ever gets hot?

Well I never checked, but currently with that fan running continuously, I would hope it doesn’t ! :slight_smile:

1 Like

So for the sake of testing, I tried just swapping the fan, without any additional thermal management complications. I ordered the first 50x50mm 24VDC quiet fan I could find:

As a reference I captured the sound level at the fan output with the original setup: around 76dB

While I was recording this, on a hunch I tried removing the fan from its housing while it was turning, and that’s when I realized that the horrible noise of the Huanyang VFD is not actually the fan’s ! It’s the sound of the air making its way through the (giant!) heatsink fins inside the VFD (that thing is massive).

For no good reason I decided to cut parts of the air intake grid underneath the VFD, to see if that helped (DON’T DO THIS, don’t insert your fingers, be safe, etc…)

and since I had bought a new fan and standalone testing seemed to show it was a bit quieter, I removed the stock one and installed it (soldered it in place)

Results are slightly disappointing, the sound is down to about 72dB (well, that’s still ~50% quieter)

EDIT: I forgot to mention also that just removing the fan cover improves the noise level.

I don’t see a good reason to keep that piece of plastic, so off it goes.

My next step will probably be to just add a resistor inthe circuit to drop the voltage so that the fan spins slower, I’m pretty sure that a lower air flow will be enough to keep that monster heatsink nice and cool.

Then I’ll probably buy one of those cheap thermal controllers I linked above too if only for the sake of trying them.


Funny that you bought the spindle/VFD to reduce the noise from the router and now you have to find a way to reduce the noise of the VFD.