why is my filament tube keep melting
Hi, not sure what you mean. I have not experienced any melting of the PTFE tubing on my P905 printer.
However in general make sure that your fans are properly working, especially the extruder fan which must keep the filament cool while in the nozzle throat.
fan is not working i order one see if that work.are they any way to test fan
Yeh, that would definitely cause problems of over heating with the extruder. It's a 12V fan so you can connect it to any 12V supply red +, black - and the fan should work.