I might have a bad part cooling fan?
I have a newly-built i3 MK3 and I suspect I might have gotten a bad blower fan, the one that cools the part as its printing. The first self-test that I performed went fine, finished all of the calibration without any issues. I printed the tree frog to make sure everything was working, and I heard some unusual noise from the blower fan when it turned on. Kind of an electronic noise, almost like it was struggling.
When the tree frog finished, there was some artifacts on the belly that indicate the part didn't get enough cooling, like the PLA was curling upward during printing. I tried a second print, this time 3D Benchy. After completing the first layer, the printer paused due to a fan error. The fan wasn't starting. I checked the connection in the electronics box and it was fine. Tried resuming a print and it errored out again. I manually turned on the fan to 255 in settings and it started, but it was making the struggling noise. It finished the rest of the print, but it had the same curling issue that looked like the part wasn't getting enough cooling.
After that, I set the fan speed to 255 again in settings and measured the voltage at the fan (the solder pads under the sticker) between + and - with a meter and I was reading 5 volts. The reading between "S" (I assume it's a tach/speed sense wire to report to the EINSY board) and - was 2.5 volts, which I think indicates it's running at half-speed. Also, any attempt to re-run the self test would pass the first test (hotend fan) and fail on the second fan (blower) with the error "front/left fans swapped". I tried swapping the connectors and it didn't make any difference, I'm pretty sure they were plugged in the right way around since it passed the test the first time and the controls correspond to the correct fans.
So I guess I'm looking for a someone to sanity check my logic here. Anyone else run into this? Should I order a new fan? Can I order one from Prusa Research or should I go digging through Mouser/Jameco/Digikey? Would Prusa Research ship me a new one since this one appears to be dead on arrival?
Re: I might have a bad part cooling fan?
You could try turning the fan on and watching it to see if the speed seems to change or shut off but that may take a while.
gave you contacted Prusa to see if they will just send you a new fan?
Re: I might have a bad part cooling fan?
The fan doesn't turn on by itself anymore. If I turn it on, it makes a whining noise and doesn't spin, but if I give it a little push, it'll start spinning. Sounds pretty dead to me and I'll be reaching out to Prusa later today to see what they can do for me.