I believe lifts are treated as locks, so not only do you not check for ambush in them
you can also enter a lift and move down the shaft, and then deploy out of the lift at the end of the same exploration turn.
You can do this because the lock function is ignored during exploration turns.
During combat alert the lift cars can't have both hatches open in the same turn, just like any other locks. So you have to get in and move to the other end, then wait for your next turn to leave. (If the car isn't at your end of the shaft to begin with, that's another turn gone -- as anyone waiting for a parking-garage elevator knows.)