My 2005 mustang convertible passenger side back window will not roll up ?

SOURCE: Window motor rolls down but not up.

I think that the switch itself is losing contact. By switch I mean the button you are depressing to roll up the window.

SOURCE: Passenger side window not rollin up properly. 2004 Mustang

i think ur window power motor need to change

SOURCE: passenger window doesn't go up, it only goes down.

Unfortunately, this is a hit or miss problem with your generation of Taurus window motors. I am assuming it is Power windows. If it is not Power windows it could have come of track and/or hit a snag. To get a better look you will need to remove the door panel by the screws in the door handle,etc.. and clips around the frame of the door panel. Once removed, there will be a a few places to see what is actually happening when you try to roll the window up.. If it is power windows the true work is rolling UP the window,as gravity is what rolls it down. If you SEE the motor spinning but the window is stationary, you have a snag. If it isnt spinning you can get a new motor from a dealer or even a junkyard. If it is Manual windows.. You SHOULD HOPEFULLY see where and how the window is catching and not rolling up.. hope this helps and good luck!

SOURCE: mustang rear window...fuse or motor?

first check the fuse.if its good then check the window motor by pressing the button and if you dont hear the motor going theres your problem, needs to be replaced.  unfortunatly the motor isnt sold by itself you got to buy the window regulator. here is a pic. of the part

SOURCE: 04 taurus Power Windows, passanger side goes down, not up, new mo

It is most likely the switch itself. since the down works that means that there is power going to the switch. So, the up position switch is probably worn out.