Spindle Control Box Noise, Hot Fan

After the spindle had been turned on for a couple mins or so, I started hearing a higher pitch noise than normal. found it was coming from the control box for the spindle so I turned it off.

I had not used my CNC today yet at all btw.

When I opened the door, the center of the fan was quite hot.

The VFD digital readout thing said F133 I believe. power cycled it a few times, now it says F394. And now when I power it down, the fan center is only warm.

What do you think happened/is happening? Something I should do so I don’t damage anything, like replace fan?

Anyone know what the F codes on the controller digital readout means/should be reading?

Thanks for any advice!

Best Regards,
@jjneeb :slight_smile:

The fan you are talking about is the 4" one on the box, not one in the VFD itself, right?

The VFD doesn’t have anything to do with the fan on the box, it just turns on when you power up the spindle control box. It sounds like the bearings might be going out on that fan.


My machine is almost 5 years old. I just had to replace that fan - mine would randomly stop spinning. It was about $25 from Amazon for a new one, so not a big deal.


@GarthJones could I trouble you to share the Amazon item here that you went with? Thanks!

Yes @jjneeb the 4” one is what got hot. Any special specs /connecyor you know on that fan for replacement?

I put spade connectors on the wires and had to file the connectors I had down just a little so they would fit in the slots - it worked just fine.

You might want to check the code on your fan and make sure this is a suitable replacement. It likely is, but just in case Avid has changed things…

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The main thing is it’s a 220v AC fan. You can get them lots of places, including AVID. I would either get them from AVID, or Digikey if it were me just to try and not get a really cheap one. One the other hand, when a fan goes out, it usually makes itself known pretty loudly, and they aren’t hard to replace, so if you do get a cheap one it’s easy to replace.

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@GarthJones Thank you so much! I really appreciate the help.

Thank you Jim for the help! I ordered one quick here to get here tomorrow, but if it is flakey I’ll do as you recommend.

Also I called Avid today and they said this fan is basically a redundancy since the VFD has its own fan, and that I can run the machine without the “extra” fan as long as its not in an oppressively hot shop. I just had some quick work today and ran it with the door ajar just fine. Cheap replacement will go in tomorrow.

Thanks again!

Here’s a similar fan for about what I paid from Amazon from Digikey. They just don’t seem that expensive.

I’m glad you called Avid, Ryan. I knew there is a fan in the VFD, but I didn’t know they considered the ‘cheap’ fan as potentially extra.

FWIW, my fan from Amazon has been running for several weeks without a hitch.



Looks like the recommended fan has ball bearings. Bushings don’t last as long. Also do some basic maintenance and blow out both boxes a couple times a year

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Thanks! Just did the blow out per your recommendation.
Who put all that dust in there? :slight_smile: