https://youtube.com/shorts/fL-yFUj1n...YHQUMUGhKZEatM
Various videos on YouTube about clearing the sills- volvo decided they should be vented, to prevent moisture buildup in them. What actually happens is leaves and other debris gets into the vents under the window screen, down the tubes in the a-pillars and then into the sills, blocking the drain holes, this then traps water and the sills rust from the inside out.
There are access plugs on the inner sill and another at the end of the sill inside the rear wheel arch.
Cheers