Nozzle (left) fan always running on maximal speed, preventing nozzle to heat up to desired temperature
 
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Nozzle (left) fan always running on maximal speed, preventing nozzle to heat up to desired temperature  

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Jui-Chun Liao
(@jui-chun-liao)
Active Member
Nozzle (left) fan always running on maximal speed, preventing nozzle to heat up to desired temperature

I own an Original Prusa MK2S. 

Recently, the extruder stopped to heat up over 115°C and returning a "preheat error". 

I found that the nozzle fan (on the left side) always running at maximal speed when temperature is over 50°C, which cools down the nozzle's temperature too much. Thus, nozzle can not be heat up over 115°C. 

I was able to reach 215°C by unplugging & replugging the fan's cable on Rambo Mini board every 5 seconds. 

Is there any solution for this problem?

I've tried: 1) reflash the firmware 

2) replace the nozzle fan, heating element & thermistor.

None of previous action did work.

 

Posted : 30/04/2019 8:11 pm
JoanTabb
(@joantabb)
Moderator
RE: Nozzle (left) fan always running on maximal speed, preventing nozzle to heat up to desired temperature

That is very odd. Can we see a photo of the extruder and fan?

I try to make safe suggestions,You should understand the context and ensure you are happy that they are safe before attempting to apply my suggestions, what you do, is YOUR responsibility. Location Halifax UK...
Posted : 30/04/2019 10:25 pm
Jui-Chun Liao
(@jui-chun-liao)
Active Member
Topic starter answered:
RE: Nozzle (left) fan always running on maximal speed, preventing nozzle to heat up to desired temperature

Posted : 01/05/2019 7:46 am
alexander.s27
(@alexander-s27)
Estimable Member
RE: Nozzle (left) fan always running on maximal speed, preventing nozzle to heat up to desired temperature

I found that the nozzle fan (on the left side) always running at maximal speed when temperature is over 50°C,

That´s pretty normal and exactly what it is intended to do and presumably always did until something odd happened.

Most likely a wiring error of some kind or a dying heat cartridge or temperature misreading for some reason.

That fan running slower heat would creep up the hotend and cause an extruder jam.

 

Posted : 01/05/2019 11:16 am
Jui-Chun Liao
(@jui-chun-liao)
Active Member
Topic starter answered:
RE: Nozzle (left) fan always running on maximal speed, preventing nozzle to heat up to desired temperature

In the past, the left fan didn't always run at maximal speed. When the extruder's temperature was between 50°C to 100°C, it run at about half speed. So the temperature was able to go up. The fan run at maximal speed when temperature was close to 200°C.

On that time, my printer didn't have this heating failure problem and it was printing well.

Posted : 01/05/2019 6:21 pm
alexander.s27
(@alexander-s27)
Estimable Member
RE: Nozzle (left) fan always running on maximal speed, preventing nozzle to heat up to desired temperature

Then your printer is not an original Prusa or someone messed around with it before. No matter what,  on all E3D  hotends the fan should run as explained before and exactly as yours does.  

This post was modified 3 years ago by alexander.s27
Posted : 01/05/2019 9:28 pm
vintagepc
(@vintagepc)
RE: Nozzle (left) fan always running on maximal speed, preventing nozzle to heat up to desired temperature
Posted by: alexander.s27

Then your printer is not an original Prusa or someone messed around with it before. No matter what,  on all E3D  hotends the fan should run as explained before and exactly as yours does.  

You may be on to something there. In his pictures that definitely is not a stock E3d hotend (look at the nozzle). If one has a knockoff hot end I'd start by suspecting that or its heater cartridge...

Posted : 01/05/2019 11:06 pm
Jui-Chun Liao
(@jui-chun-liao)
Active Member
Topic starter answered:
RE: Nozzle (left) fan always running on maximal speed, preventing nozzle to heat up to desired temperature

I accidentally broken the nozzle throat in the original E3D hotend, so in my previous pictures, all metal parts in extruder were replaced one.

After replacing the original hotend, my MK2S was working fine for a few days. I remember that the left fan was not running at maximal speed all the time, since its sound wasn't as loud as it was running at maximal speed.

After that, the extruder heating problem came back. 

If I understand well, this issue can be solved by replacing the heating element ?

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Posted : 02/05/2019 1:42 am
Vojtěch
(@vojtech-3)
Honorable Member
RE: Nozzle (left) fan always running on maximal speed, preventing nozzle to heat up to desired temperature

In the pictures at the start of the thread I see the heatsink touching the heater block. That is your problem right there. There is supposed to be a heat break to prevent heat leaking from the block to the sink. There must be a 2.1mm or more gap between the sink and the block corresponsing to the thin throat on the heatbreak. They must not be touching.

By the way, that's not a E3D v6 nozzle you've go there. And I wonder if the heatsink is an original one, too, it's way shinier than what E3D sells.

Posted : 02/05/2019 7:40 am
Jui-Chun Liao
(@jui-chun-liao)
Active Member
Topic starter answered:
RE: Nozzle (left) fan always running on maximal speed, preventing nozzle to heat up to desired temperature

vojtech-p6, 

Your suggestion resolve my heating problem! Thanks a lot!!

Posted : 23/05/2019 10:43 pm
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