This has been discussed in past,
More on the original XWeb site than on here.
Herzel, since you've asked...
First thing is to make sure your electrical system is up to par.
Insure your ground wire from the battery is good and insure you have
a beefed up +12V line going
to the distribution point in your car. (in other words, run that 10Ga wire in parallel with the 10Ga
wire that runs from your battery to your fuse box tie point)
The window switches are powered from your fuse box, so the above is important.
Next, be sure your window switches are clean on the inside. Dirty contacts here will cause issues.
Then be sure your windows run up/down the tracks smoothly. I use silicone spray lubricant inside
the window runners (both front and back side and down into the door as far as I can reach) and insure
the glass has a smooth transition physically.
This is all I personally had to do and my windows go up/down fine.
There are 2 other things you can do if you still don't have the desired results. One being lubricate the
window motors. This is not easy to do because it requires door and window (motor) dis-assembly. :mallet:
The second thing is to add relays. I see Greg mentions 2 relays and he is correct, BUT they must be
SPDT relays. (single pole, double throw)
They must be wired in a way that (when activated in 1 direction) will present the voltage to the motor
as "+" and "-", and when activated in the other direction present the voltage
as "-" and "+". (just the opposite) If you need help with that little circuit, just let me know.
Good luck, and let me know your thoughts.