I replaced my power window regulator on 1998 ford mustang mut now the switch works the opposite way and the window rolls half way down only

It's probably a bad switch.

It can be issue with motor itself.If its not going up,then how its working down.But still it feels like weak window motor or is issue with power window switch.Get the voltage tested at switch and motor.Also try another working window motor at not working window side.
==========For more troubleshooting i suggest go through the help links mentioned below:-----
Its complete details with troubleshooting steps:------
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These details will help.Thanks.

I have a 1990 Mustang with power windows. When i first got the car the windows rolled up and down fine, then the passenger one started going up slower than the driver one. When i needed to fix my power locks i had them change the window motor in the passenger side. Now the passenger window rolls up faster than the driver one. The problem is the window motors.......and about the motors still running: the switches probably need to be replaced as well. I can almost guarantee this will solve your problem:)

window regulator could be pushing the window up too much. until you replace it, don't roll you're window up all the way.

Replace tue fuse ...

I am more likely to look for a fusible link ... do you have power to other systems?

If your window rolled down than means your window regulator is getting power. It's most likely your switches are bad.

When you use the down switch it supplies power to your window regulator. When you use the up switch it supplies power also but the polarities are switch which causes the window to roll in the opposite direction.

Sounds like your up switch is not making a complete connection to make your window roll back up.

For parts, check this LINK.

Good luck.

change the switch

you going to have to take it apart to get to it, is not that hard but time consuming; the parts is cheap. The common problems with those is the regulator is worned and need replacing. regulator is a window track, it keep the window in it track and when it become worned it get sloppy. hope that help some

does this happen from both the Driver's & RR passenger's window switch?
if from both check for power at the window motor. If no power at the motor for only one switch, replace suspect switch. if power at the motor, remove motor from regulator asy. & and motor again in both direction. If motor and switches good, replace the regulator asy.

check the pwer switch. if you don't detect any sign of live. then you have to open the door panel to check the motor. most likely the motor or the "T" rail cable is broken.