There have been a few modifications on the Grand Marquis and Crown Victoria over the years but the window regulators have remained the same. There are two cables that pull the glass up and down on a metal cross bracket. If the regulator breaks the glass will usually fall into the door and you will hear a crunching, grinding sound for 5-10 seconds when you press the window switch. You will need to replace the regulator and this involves drilling out rivets that are set in the glass.
Window switches are not a common problem. The other issue is the window motor/gears. For the 1992-1998 when the spacers in the gear need to be replaced you will hear the motor turn for as long as you press the switch. Prior to the spacers breaking up completely they become more oval than round and you may notice the glass slows down about a third of the way up and again at the next third of the way up. For these models we can change the spacers, the motor seldom is a problem. The 1999 and newer use a sealed motor with nothing to change inside. You will need to replace the entire motor if you get no response when you press the window switch. 727/410-9995 if we can help.
http://www.dslreports.com/forum/r29077983-Power-window-problem-UPDATE
