Power windows won't go down after a drive

[911 Rod]

Electrical gremlins drive me nuts.

After driving my 86 911 for an hour or so the windows won't go down.

They want to, but really struggle for the first couple of inches. If they go down a little you can get your fingers in and help them. Bottom 80% and up they are fine. In the garage they go up and down great all day long.

As well there are 2 other problems. Parasitic draw killing my battery and power windows work after you remove the key and open the door.

I took the door switch apart and cleaned it and it appears to have fixed the windows working after removing the key.

Was the switch also the culprit of the other 2 problems?

Driving me f###ing nuts and I can't drive the car because it's winter here.

[Alex599]

Have you tried degreasing, regreassing the regulators? They get seized up after 30 plus years!

[911 Rod]

I have the door cards off right now to check everything and they look great with lots of lube. Super fast with the car in the garage. Go up and down 20 times without hesitation. No glitches.

[911 Rod]

Could the sticky door switch create a load on the motor to make it sluggish?

[Windsor4273]

My passenger door one did that for years. I figured it was just the regulator getting tired. Then the door switch on the driver's side went out that controls that window, and when I replaced it the window went up and down like it should.

[911 Rod]

Replaced all 3 switches and the relay.

[911 Rod]

Even though the window goes up and down fine in the garage, I took out the regulator to inspect.

Everything is perfect. I'll clean and re-grease, but it looks like I wasted my time.

[dw1]

The windows not working after driving thing happened to me and it turned out to be a vibration-driven intermittent at the fuse, probably exacerbated by some oxide on the fuse contacts.

Just an idea for one more thing to look at.

[Tremelune]

If it ain't the fuse, run a line directly from the battery to the switch(es). If they move with gusto when you touch the hot wire to them, it's the switch(es).

They are terrible switches, and tend to crack at the pivot point, which means you need to torque and wiggle them to get the contacts to touch well. If you lose the driver's side switch, sometimes the passenger side window is impacted as well, as the wiring goes through both. Ultimately a bad design that hasn't been corrected.

[911 Rod]

Thanks for the help guys.

I understand what you are suggesting, but why does it go back to normal when the car sits?

[DanielDudley]

Check the fuse, clean the contacts and check the screws. Check the ground. If it is a common ground with other items, and it has a continuity issue, then it is taxed and getting hot, because it is being used by a different circuit.

It's most likely a continuity issue, so it is a bad connection, or a poor splice, poor power source, switch or ground. You start at the power source, and trace it to the end. And it's a bit like a legal document, the more you look at it, the more sense it makes. Getting a wiring diagram will help you.

[911 Rod]

Originally Posted by DanielDudley

Check the ground. If it is a common ground with other items, and it has a continuity issue, then it is taxed and getting hot, because it is being used by a different circuit.

This would make sense as it is doing it after a long drive only. Thanks for the tip.