Ochen

The driver side door seems to only be able to lock, however, it will not unlock by itself. There is a small hissing sound coming from the door when it tries to unlock. The passenger side door works fine and there doesn't seem to be a problem with the pump.

Tom_Boy

Believe that will actually be the actuator mechanism. They are repair kits on E-Bay or the assembly is available from MBUSA. There is also a number of good videos on YT that show you how to do the R&R. Pack a sack lunch, it's a day-long and complex job. Some say you have to pull the window, others say no... I dunno. I paid to have it done.