Gen2 window motor component??

[disco stu]

Hi all. Looking to identify this component inside window motor, picture down lower

Rear window motor stopped working on my NL so I pulled it apart to see what was happening. It was behaving really weird even with no load on it (pulled apart on the bench, so gearing inside removed), like it was powered by a battery with no charge left-it would move for a second and slow to a stop. Leave it for a a while and it would then do the same. It wasn't power source causing this.

My mind went to something capacitance related, but I'm no expert on electronics. All connections were fine, zero resistance etc. Left it for a few weeks

I just decided to have another play, and noticed this large copper sandwich type plate inside. I bridged the contacts with a bit of steel and tried again and what do you know-ran like a dream. So I've found what is causing the issue, but I'm confused as about what it is. Not something I've seen before

The plate I'm talking about has the arrow to it in the picture below. Not sure why it doesn't want to insert the picture here

It is a sandwich type construction, with copper plate either side. One side is connected to the power input wiring for one side of motor and the other plate goes to the brush. The other brush on the motor goes straight to the wiring plug without anything like this.

There is a ceramic capacitor between both inputs in another spot, so that isn't what this component is.

My thinking to get the motor working is to just bridge the two sides of the plate with solder, cause I just want the window to work (especially in this rain!), but I would like to know what this is before bypassing

Anyone got any ideas what the purpose is?

Appreciate any advice

[disco stu]

I think I've figured out that this part is a thermal trip/ptc thermistor, designed to reduce current on the window shutting or someone's arm in the window. I could just throw another ptc thermistor in the wiring to achieve the same result....if I can work out what sort of specs

I'm also thinking that this part is the often the cause of issues with windows that go up a little at a time and needing a break to get all the way. The current through that motor without any load would obviously have been low, so that indicates that they can get old and stop functioning currently causing issues.

[Kingbrown]

My best guess is a solid state fuse. Sometimes referred to as a 'Poly Switch' amongst others.

Here's an example:

https://m.littelfuse.com/products/polyswitch-resettable-ptcs/battery-strap.aspx

The likes of Jaycar should be able to supply an equivalent if you can establish what the normal running current is vs the stall current of your window motor.
I'd suggest the fuse trip current should be approx twice the loaded running current of the window motor.

[disco stu]

Thanks for that. You've got me on the right track. I had figured out that they must be a ptc thermistor, but that wasn't helping much finding simmering else to do the job.

Jaycar website doesn't seem to be much help, only had low power versions for speakers

I know the stall current is 8.5a, I'm just not sure what the running current is on that motor

I'll keep doing some searching.Thanks for the help

[disco stu]

So I've figured out that jaycar does actually what they call auto reset fuse, their sensor search sucks bad so I couldn't find it. Got them in 5 and 7.5a. Just trying to work out what the normal running current would be for this motor to choose one of these to go on it.

At 8.5a stall current I thought 5 might be above normal running current. But maybe I'm better off going 7.5. Just want it to shoot of quickly if the kids wind the window right up and hold the button on

[disco stu]

So it turns out the one jaycar have isn't a ptc thernistor type but a clocking one, so I'm assuming it is bimetal strip. Bought the 5a because it's response is a little variable up until over 200% of reading and stuck with it now so I've installed in the wiring

Heaps of options on eBay so if this doesn't do what it is supposed to I'll buy a few off there

I suspect this is the issue that other have had when window just stops working.