If the window goes down, the motor is obviously working OK - so the problem is most likely to be the switch....the motor simply receives positive and negative current, which is reversed to wind in the opposite direction....
Are u sure it uses +/- current? I know most cars window motors use that principle, but did u check on alfa 156 facelift interior? I'm asking because I checked at the door connectors and only found +12V on lowering the window and raising the window was 0V on that same pin.. I guess my question is how many pins is the motor? 1,2,3?
Even if the switch "clicks", it may be dirty or not fully pressed down by the lever. This is especially true for raising the window, as the levers uses the pivot, the weakest part of the switch.. Those levers seem to break down easily at the pivot...
Well, that caused my windows to refuse to close, 4 switches, 2 rear windows: all seem to fail to trigger the closing (opening all ok). The previous paragraph is my experience on why driver side switches didn't work.
But still, I didn't get the rear switches to work. These are in excellent state - don't think they are broken. No, it seems as if the "Lock" function is enabled at the driver's panel (although opening down, and red LED of the rear switches works properly). I did clean the door connections, and lock switch connections to no avail.