Dear muskox37,

Hope you're well. The most likely failure point is the steering column-mounted switch, on the right side, that controls the wipers. The reason: the switch has to be moved to activate the wipers. If the car has lived where it rains a lot (as opposed to the US southwest or Australia's interior), that switch could have reached the end of its service life.

I'd swap-in a "known good" spare windshield wiper switch. I'll bet that solves the problem. The part is #1363016 (sedan). MSRP is about $60 at a US Volvo dealer. You should be able to get one for far less at a salvage yard.

Hope this helps.

Yours faithfully,

Spook