The actuator is the thingy (a solenoid, I guess, with bells and whistles) that locks/unlocks the door lock when the juice hits it. It yanks the lock linkage one way for lock and the other way for unlock. On my 95, something went wonky in the PL's so that the actuator was activated in the lock position all the time, so it took Sampson to twist the key to unlock, and the remote didn't work at all, and the lock returned to lock by itself. Never fixed it, just pulled the fuse for the PL's.

Not responsible for advice not taken...