87 190e power window problem

[ltack1950]

my left rear window was not working when i purchased the car, took it apart found bad motor, replace it with used one. it would go down but not up on rear window control replaced switch with one i knew would work same problem change switch in front center console same thing the right passenger window works ok i think they work together.. took regulator out and hook straight to a battery it works fine, now im lost