I have been having problems with my right front window. Some days it works, some days it does nothing. On days when it does nothing, I get zero motion from the window in both directions, no signs of the motor trying to turn, nothing at all. Then the next day it works fine. The only possible correlation I have noticed is that it tends to fail on hot days.

So far I have cleaned the window switch and it's contacts, tightened the terminal screws inside the door, supplied 12v directly to the motor (works fine if I do that), and cleaned and greased the regulator and window tracks.

I do have a spair motor and regulator, but hate to swap that in until I know for sure what the root cause is.

Does anyone have any suggestions? It is very difficult to troubleshoot an intermittant failure like this.