Hotend fan continuously fails self-test  

RE: Hotend fan continuously fails self-test

Came here from Google after just completing a new MK4 kit build as well  Only thing that failed test was the hotend fan, confirming updating to firmware 5.1.0 fixed the issue.

RE: Hotend fan continuously fails self-test

Hey everyone,

I just completed assembly on my Mk4. Everything works fine, and it prints fine, but it fails the print fan test. The hot end fan passes.

However, when I want to test the heating bed, it reports it can not proceed due to a hot end fan failure.

I *think* someone made have made a booboo in the firmware. Regardless, it prints fine, and temperatures are rock solid.

I contacted support through the chat. The person advised me to 'loosen the screws on the fan'. When I reported I tried to no avail he advised :

"there might be some firmware bug causing the selftest to be too strict. I would try running a few prints to confirm that there is no error with that fan and the next firmware should solve the problem"

So that's what I will do.

Pete

RE: Hotend fan continuously fails self-test

Hi Peter, Try slackening the mounting screws a tiny bit... 

then re test, 
regards Joan

RE: Hotend fan continuously fails self-test

You beat me to it @Joantabb, I had exactly the same issue with my kit build and this was the solution that worked for me  

Posted by: @joantabb

Hi Peter, Try slackening the mounting screws a tiny bit... 

then re test, 
regards Joan

RE: Hotend fan continuously fails self-test

This is the printing fan. It is encased. Which screws do I loosen ?

RE: Hotend fan continuously fails self-test

Easy  to troubshoot.  Don't loosen any screws.  Make sure you have the latest firmware.

1) Is the fan turning?  If yes, proceed to 2).  If no, you found your problem.  The fan is bad.  Yes, you can loosen screws to see if the fan is binding, but I never had any problems.  

2) If the fan is turning, the fan has a bad tachometer.  Have Prusa send you a new fan (or get a new fan).

The fan speed is controlled by a PWM controller based on the temperature as measured by the NTC thermocouple in the heat sink.  

If loosening screws makes the problem go away, the heatsink is warped, and the fan is binding.  You need a new heatsink (and maybe a new fan).  What you can do to see if the fan is binding is to remove the fan and see if the blades turn freely.  If they don't, the fan bearings are bad and you need a new fan.  If they fan turns freely when the fan is removed, but not when it's mounted on the heatsink (with the screws tight), the heatsink is warped and you need a new heatsink.  Loosening the screws doesn't fix the problem, it simply makes the fan get looser.

I had no problems with my MK4 kit, but lots of bad parts with my XL kit.  YMMV.

I have found that Prusa support leaves much to be desired.

Steve

RE: Hotend fan continuously fails self-test

The mounting screws I am referring to, are circled in Orange in this picture

regards Joan

RE: Hotend fan continuously fails self-test

As @joantabb says - these are the screws you inserted to affix the fan. I ever so slightly over tightened mine and ended up with the same issue as you. Mine were loosened (anct I slackened the. Off and then re-tightened them more carefully) and now everything runs like a dream. 

RE:

OK, once again. His fan is a closed unit, unlike the hot end fan. Loosening it doesn’t do anything for the pressure differential  over the fan, and thus the air resistance. I *may* try removing the shroud, but I think I’ll leave well alone for a proper fix.

If the screw trick worked for this fan, I suspect you had a pinched wire.

RE: Hotend fan continuously fails self-test

This Fan is the Partcooling Fan and not the Hotend Fan.
The Topic of this Thread is about the Hotend Fan.. 

Posted by: @peter-r

This is the printing fan. It is encased. Which screws do I loosen ?

RE: Hotend fan continuously fails self-test

After taking on firmware 6.0.0 now all 5 head on my XL have print fan calibration errors. They look to spin just fine.