Expert: Ben Menard - 12/18/2009

Question
Hi, my 2001 gm Montana driver's side power window goes up fine till about the halfway point, then it slows down, the engine idle speed drops and then the window motor stops completely.

I have taken the glass out. The motor works fine with no glass.
I put some grease in the channel which holds the glass.
When I put the glass back in, the motor stalls at the halfway point again.

Do I need a new motor or is there some adjustment that needs to be made?


Answer
Hello Tom,

I doubt that the motor is the problem.  I suspect you have an issue somewhere in the "regulator" or "run channels".  

I would start by looking for a "pinch" in the front run channel.  The cause of this problem can usually be traced to a strike against the sideview mirror on the forward edge which presses the frame of the mirror against the glass run channel causing a restriction.

Occasionally, the bolts that hold the front run channel support inside the door come loose or the channel mounting bracket breaks.  You should check this area as well.

If neither of these is the source of the problem, look at the "regulator" arms.  These are the scissors-like metal arms that are actually moving as the window motor turns.  Be sure the arms are not bent in any way.

One last note.  Never use grease on a window run channel. It will attract dirt and get sticky and even hard. (you need to clean up what you have already used) Instead, use only a silicone spray.  Cheap silicone spray is as effective as expensive, so get the cheapest stuff you can find at your local Lowes, Home Depot, etc.

If these suggestions don't locate the source of the problem, send me a follow-up question with some additional information and I will see what else I can suggest.

Ben  .... the power window guy