Hi,

Have you tried going directly to the motor with a jumper wire from a battery source, like the fuse panel right next door.
That might get the window low enough to work on it.

You might have a bad relay up to the right of the instrument cluster or vent area.
There could be another switch not making its contacts come together in the neutral position, as the power switches back and forth through a combination of circuits in the drivers door arrayed switches.
The contacts are tiny and do get flaky. They need a good cleaning especially the most used one. Checking these with and ohmmeter doesn’t always mean it can carry current Faithfully, to the relay either.

I think I read someplace that the drivers door harness comes through and goes up under the dash on the left. You might find a connector that you can research the colors on.
I’m sure someone has a better diagram and another locational” address on the web that will show you how it’s wired in color.

I could not or cannot find a better one at the moment, but I have this one.
It’s down on page 12 if it doesn’t go directly there. You will see how each switch carries the circuits.

https://greenbook-archive.s3.ap-southeast-2.amazonaws.com/Volvo%20240%201989_WIRING%20DIAGRAMS.pdf?X-Amz-Content-Sha256=UNSIGNED-PAYLOAD&X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Credential=AKIAJK33YYDXXSPEUZMA%2F20200619%2Fap-southeast-2%2Fs3%2Faws4_request&X-Amz-Date=20200619T064917Z&X-Amz-SignedHeaders=host&X-Amz-Expires=300&X-Amz-Signature=46ccf09a18eaa1ef5c8b7050e9069559593ad9bd718e05b7ce38e1b60e0ba978

Have you searched for any post covering the subject?

Phil