slow window motor now not working
 

'79 911 SC
The passenger window motor has stopped working. I am going to change both switches for that side. Even if that is not it, they both feel worn out/move funny.
Previous to it stopping that side was always very slow to close. What usually makes them slow? motor wearing? grease hardening? regulator? I figure while I am in there I might as well address that, or just get a motor now if that is most likely the not working root cause.
Thanks,
Adam

Adam,

I think it's the grease hardening. I had the same issue. It ended up being the switch, but I only found that out after changing the motor. The passenger side has always been slow. Changing the motor did not change the speed. Recently it was very hot outside and I had my car sitting out to heat soak it. I think the heat improved the speed. While not as quick as the driver it was an improvement, but went slow again the next day. Hope that helps.

Grease hardening is often part of it, so you should probably clean and regrease all moving parts.

Also, the felt surface on the rubber window trim wears out and the window catches on the rubberized surface, slowing and/or stopping it. You should replace this trim with new.

It’s usually caused by a broken pivot on return spring, very common. Check bottom of your door for parts

I recently replaced my driver side window switch becasue it was to the point I had to jiggle it to get the window to work. Simple swap, and now the window moves a lot faster. I was surprised that the switch was likely corroded inside and reducing voltage to the motor. I did not do an autopsy on the old switch, it just went to the trash.

New switch, and faster window operation. I was really surprised.

Often the motor's armature shaft seizes in it's lower bushing. If you pull off the armature cover, you might see the bushing stuck on the end of the shaft. Not too hard to unstick it and have a working motor again.

Probably to late for the OP but when I needed new window switches for my 930 I found out that a VW switch was the same part at a fraction of the cost. This was years ago so, I don’t remember the model of the VW. Possibly Golf.

Check out the link below - we have several DIY tech articles on the window and the regulator itself.

https://www.pelicanparts.com/911/911tech_articles.htm