this is how i'd do it
the idea is:
fan switches relays... two which switch the position of the ground and the power line to the actuator. changeing its direction (fan on=extend, off = in) and one wich determines wich controle switch (fan on = monitor pistion full out, fan off = monitor piston full in) is monitored
this controle switch operates a 4th relay that switches the main power off if the pistion is at the end of its travel.
maybe not the most refined system but the logic could be used for something more advanced.