I have a 1998 XLT

Symtoms:

Power locks works OK from the drivers side (both doors, up and down)

Power locks only works down on the passinger side, not up.

There is a noise like it is trying to go up when the passinger up button is pressed, but both sides will not go up when the passinger up button is pressed.

There is no Key Fob for this truck if that matters.

Could this be a dirty switch?

 

There is a fix for the window switch in the DIY's, use the same process.

My Expy had a simular situation with the driver side. I had to clean the contacts and bend the spring clip a little......problem solved.

Good luck