i3 mendel emotiontech Z axis home don't work

My printer is working correctly with this setting, but when I get home Z axis does not work. This must be done manually.
After clicking on the Home key can Z-axis approach a little bit toward the stopend, then hangs and engines emit unpleasant sound.
I tried all possible settings but no help ... Please help

First thing to check would be the wiring on the Z axis limit switch.

Endstop is connected correctly, i wrote before - the printer works correctly but don´t get to the endstop on Z axis, this must be done manually

Edited 1 time(s). Last edit at 11/21/2013 12:53PM by morib.

If the motors are making a lot of noise, that probably means the Z carriage is running into something before it triggers the limit switch.

Either:

1) the limit switch is set too low
2) there is something (like the top of a rod coupler) blocking the Z before the carrage gets to the proper location.
3) the limit switch is not wired right or it's plugged into the wrong connector
4) the firmware is not set up to recognize the limit switch
5) there is crud on the Z rods that is hanging up the nuts in the carrage