Cannot print two times in a row

[frntz 0]

Hello everyone,

I notice that I cannot print on my Ultimaker 2+ two times in row, it will always failed the second print by either printing the first layer then failed or cannot  ... each time I have to remove the filament which is always stuck between bowden tube and the isolator and wait 1 hour or so for the printer to cool down. Gr5 Moderator mentioned an underextrusion issue which falls in my case I guess:

Quote

18) third fan broken.  This tends to cause complete non-extrusion part way through a print.  In the rear of the head for UM2 and the front of the head for UM3.  Without this fan several things can go wrong.  It can take a while as usually you also need several retractions to carry the heat upwards.  There are a few failure mechanisms and I don't understand them all.  One of them is probably that the molten PLA spreads out above the teflon and sticks to the metal in a core or fills the gap at the base of the bowden in UM2.  Later it cools enough to keep the filament from moving up or down.

 

I notice that sometimes the rear fan is not working at the beginning of the first print and then is always one, is it the normal behaviour ? Should I buy a new fan ?

Is someone has the same issue has myself and what can I do to fix this ?

 

 

My Printer : UM2+

My Firmware : _3.3.3

[geert_2 557]

The little rear fan (nozzle-cooling) should always be on when printing (when the nozzle is above 40°C). If not, check if there are no hairs and strings of filament or dust stuck in it. Check the connections and wires. If the bearings would be worn-out, or the wires broken, replace.

 

[frntz 0]

Thank you so much for your reply I've changed the rear fan which now is on when the nozzle is above 40°C !